Shielded Electrical Cable

ABSTRACT

A shielded electrical cable includes conductor sets extending along a length of the cable and spaced apart from each other along a width of the cable. First and second shielding films are disposed on opposite sides of the cable and include cover portions and pinched portions arranged such that, in transverse cross section, the cover portions of the films in combination substantially surround each conductor set. An adhesive layer bonds the shielding films together in the pinched portions of the cable. A transverse bending of the cable at a cable location of no more than 180 degrees over an inner radius of at most 2 mm causes a cable impedance of the selected insulated conductor proximate the cable location to vary by no more than 2 percent from an initial cable impedance measured at the cable location in an unbent configuration.

TECHNICAL FIELD

The present disclosure relates generally to shielded electrical cablesfor the transmission of electrical signals, in particular, to shieldedelectrical cables that can be mass-terminated and provide high speedelectrical properties.

BACKGROUND

Due to increasing data transmission speeds used in modern electronicdevices, there is a demand for electrical cables that can effectivelytransmit high speed electromagnetic signals (e.g., greater than 1 Gb/s).One type of cable used for these purposes are coaxial cables. Coaxialcables generally include an electrically conductive wire surrounded byan insulator. The wire and insulator are surrounded by a shield, and thewire, insulator, and shield are surrounded by a jacket. Another type ofelectrical cable is a shielded electrical cable having one or moreinsulated signal conductors surrounded by a shielding layer formed, forexample, by a metal foil.

Both these types of electrical cable may require the use of specificallydesigned connectors for termination and are often not suitable for theuse of mass-termination techniques, e.g., the simultaneous connection ofa plurality of conductors to individual contact elements. Althoughelectrical cables have been developed to facilitate thesemass-termination techniques, these cables often have limitations in theability to mass-produce them, in the ability to prepare theirtermination ends, in their flexibility, and in their electricalperformance.

SUMMARY

The present disclosure is to directed to high speed electrical datacables. In one embodiment, a shielded electrical cable, comprises aplurality of conductor sets extending along a length of the cable andbeing spaced apart from each other along a width of the cable. Eachconductor set includes one or more insulated conductors. The cable alsocomprises first and second shielding films disposed on opposite sides ofthe cable. The first and second films include cover portions and pinchedportions arranged such that, in transverse cross section, the coverportions of the first and second films in combination substantiallysurround each conductor set. The pinched portions of the first andsecond films in combination form pinched portions of the cable on eachside of each conductor set. The cable further comprises a first adhesivelayer bonding the first shielding film to the second shielding film inthe pinched portions of the cable. The plurality of conductor setscomprises a first conductor set that comprises neighboring first andsecond insulated conductors and has corresponding first cover portionsof the first and second shielding films and corresponding first pinchedportions of the first and second shielding films forming a first pinchedcable portion on one side of the first conductor set. A selected one ofthe insulated conductors has a wire diameter no greater than 24 Americanwire gauge (AWG), and a transverse bending of the cable at a cablelocation of no more than 180 degrees over an inner radius of at most 2mm causes a cable impedance of the selected insulated conductorproximate the cable location to vary by no more than 2 percent from aninitial cable impedance measured at the cable location in an unbentconfiguration.

In one configuration, the wire diameter of the selected insulatedconductor may be no greater than 26 AWG, and wherein a transversebending of a cable location of no more than 180 degrees over an innerradius of at most 1 mm causes the cable impedance of the selectedinsulated conductor proximate the cable location to vary by no more than1 percent from the initial cable impedance. In another configuration,the selected insulated conductor may be part of a selected one of theconductor sets that includes at least two insulated conductors eachhaving a wire diameter no greater than 24 AWG and a nominal differentialimpedance of 100 ohms. In such a case, the transverse bending of thecable causes a differential cable impedance of the selected conductorset proximate the cable location to vary by no more than 2 ohms from aninitial differential cable impedance measured at the cable location inthe unbent configuration. Also in such a case, the wire diameter of theat least two insulated conductors may be no greater than 26 AWG, andtherefore the transverse bending of a cable location of no more than 180degrees over a second inner radius of at most 1 mm causes thedifferential cable impedance of the selected conductor set proximate thecable location to vary by no more than 1 ohm from the initialdifferential impedance.

In any of the embodiments above, the selected insulated conductor mayhave a nominal cable impedance of 50 ohms, and in such a case the cableimpedance of the selected insulated conductor proximate the cablelocation varies by no more than 1 ohm from the initial cable impedance.In any of these embodiments, the cable may further comprise a bend of atleast 45 degrees around a fold line that extends across a width of thecable, wherein the bend has an inner radius of at most 5 mm. In such acase, the bend may be at least 90 degrees and conforms to geometry of astructure that encloses the cable, and/or the bend may be at least 180degrees and the fold line is at a fold angle relative to a longitudinaledge of the cable such that the cable turns at a turn angle in responseto flattening of proximate regions before and after the bend to a plane.In the latter case, the fold angle may be 45 degrees, and the turn angle90 degrees.

In another embodiment, a shielded electrical cable comprises a pluralityof conductor sets extending along a length of the cable and being spacedapart from each other along a width of the cable. Each conductor setincludes one or more insulated conductors. The cable also comprisesfirst and second shielding films disposed on opposite sides of thecable. The first and second films including cover portions and pinchedportions arranged such that, in transverse cross section, the coverportions of the first and second films in combination substantiallysurround each conductor set. The pinched portions of the first andsecond films in combination form pinched portions of the cable on eachside of each conductor set. The cable further comprises first adhesivelayer bonding the first shielding film to the second shielding film inthe pinched portions of the cable. The plurality of conductor setscomprises a first conductor set that comprises neighboring first andsecond insulated conductors and has corresponding first cover portionsof the first and second shielding films and corresponding first pinchedportions of the first and second shielding films forming a first pinchedcable portion on one side of the first conductor set. A selected one ofthe insulated conductors has a wire diameter no greater than 24 Americanwire gauge (AWG), and a transverse bending of the cable at a cablelocation of no more than 180 degrees over an inner radius of at most 5mm causes an insertion loss of the selected insulated conductorproximate the cable location to vary by no more than 0.5 dB from aninitial insertion loss measured at the cable location in an unbentconfiguration.

In this embodiment, the cable may further comprise a bend of at least 45degrees around a fold line that extends across a width of the cable,wherein the bend has an inner radius of at most 5 mm. In such a case,the bend may be at least 90 degrees and conforms to geometry of astructure that encloses the cable, and/or the bend may be at least 180degrees and the fold line is at a fold angle relative to a longitudinaledge of the cable such that the cable turns at a turn angle in responseto flattening of proximate regions before and after the bend to a plane.In the latter case, the fold angle may be 45 degrees, and the turn angle90 degrees.

In another embodiment of the invention, a shielded electrical cablecomprises a plurality of conductor sets extending along a length of thecable and being spaced apart from each other along a width of the cable.Each conductor set includes one or more insulated conductors. The cablealso comprises first and second shielding films disposed on oppositesides of the cable. The first and second films include cover portionsand pinched portions arranged such that, in transverse cross section,the cover portions of the first and second films in combinationsubstantially surround each conductor set. The pinched portions of thefirst and second films in combination form pinched portions of the cableon each side of each conductor set. The cable further includes a firstadhesive layer bonding the first shielding film to the second shieldingfilm in the pinched portions of the cable. The plurality of conductorsets comprises a first conductor set that comprises neighboring firstand second insulated conductors and has corresponding first coverportions of the first and second shielding films and corresponding firstpinched portions of the first and second shielding films forming a firstpinched cable portion on one side of the first conductor set. Anapplication of a force on the cable, the cable being simply supportedbetween two supporting points that are 3.0 inches apart and the forcebeing applied midpoint between the supporting points, results in adeflection in the direction of the force of at least one inch. Theforce, measured in pounds-force, does not exceed the sum of individualforces for each of the insulated conductors, the individual forces beingequal to 11000 times a wire diameter cubed of the respective insulatedconductor, the wire diameter being expressed in inches.

In one arrangement, the wire diameter may be no greater than 24 Americanwire gauge (AWG). In any of these arrangements, the maximum force mayoccur when the deflection is between 1 inch and 1.5 inches. Similarly,the cable in any of these arrangement may further comprise a bend of atleast 45 degrees around a fold line that extends across a width of thecable, wherein the bend has an inner radius of at most 5 mm. In such acase, the bend may be at least 90 degrees and conform to geometry of astructure that encloses the cable. Or, in such a case, the bend may beat least 180 degrees and the fold line is at a fold angle relative to alongitudinal edge of the cable such that the cable turns at a turn anglein response to flattening of proximate regions before and after the bendto a plane. For example, the fold angle may 45 degrees, and the turnangle 90 degrees.

In another embodiment of the invention, a cable assembly comprises ashielded electrical cable. The cable comprises a plurality of conductorsets extending along a length of the cable and being spaced apart fromeach other along a width of the cable. Each conductor set includes oneor more insulated conductors. The cable also comprises first and secondshielding films disposed on opposite sides of the cable. The first andsecond films include cover portions and pinched portions arranged suchthat, in transverse cross section, the cover portions of the first andsecond films in combination substantially surround each conductor set.The pinched portions of the first and second films in combination formpinched portions of the cable on each side of each conductor set. Thecable further includes a first adhesive layer bonding the firstshielding film to the second shielding film in the pinched portions ofthe cable. The plurality of conductor sets comprises a first conductorset that comprises neighboring first and second insulated conductors andhas corresponding first cover portions of the first and second shieldingfilms and corresponding first pinched portions of the first and secondshielding films forming a first pinched cable portion on one side of thefirst conductor set. The cable assembly further comprises an electricalconnector encompassing at least the bend in the cable, wherein at leastone of the insulated conductors is electrically coupled to at least onecontact of the electrical connector.

In one arrangement, the electrical connector may comprise an overmoldformed onto the cable and/or a multi-piece housing. In any of thesearrangements, the connector may comprise a paddle card connector.Similarly, the bend may be at least 90 degrees around the fold line inthese arrangements, and the inner radius of the bend may be at most 1mm. In any of these arrangements, the connector may disposed on an endof the cable and/or a middle portion of the cable. The insulatedconductors may have a wire diameter of no more than 24 American wiregauge (AWG).

In any of these variations, the cable may further include a second bendnot encompassed by the electrical connector, the second bend being of atleast 45 degrees around a second fold line that extends across a widthof the cable, wherein the second bend has an inner radius of at most 5mm. The second bend may be at least 90 degrees and conforms to geometryof a structure that encloses the cable assembly, and/or the second bendmay be at least 180 degrees and the second fold line is at a fold anglerelative to a longitudinal edge of the cable such that the cable turnsat a turn angle in response to flattening of proximate regions beforeand after the second bend to a plane. In such a case, the second foldangle may be 45 degrees, and the turn angle is 90 degrees. In any ofthese embodiments, the at least one conductor set of the respectivecables may be adapted for maximum data transmission rates of at least 1Gb/s.

These and various other characteristics are pointed out withparticularity in the claims annexed hereto and form a part hereof.Reference should also be made to the drawings which form a further parthereof, and to accompanying descriptive matter, in which there areillustrated and described representative examples of systems,apparatuses, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example shielded electrical cable;

FIGS. 2 a-2 g are front cross-sectional views of further exampleshielded electrical cables;

FIGS. 3 a-3 d are top views that illustrate different procedures of anexample termination process of a shielded electrical cable to atermination component;

FIGS. 4 a-4 c are front cross-sectional views of still further exampleshielded electrical cables;

FIGS. 5 a-5 c are perspective views illustrating an example method ofmaking a shielded electrical cable;

FIGS. 6 a-6 c are front cross-sectional views illustrating a detail ofan example method of making a shielded electrical cable;

FIGS. 7 a and 7 b are front cross-sectional detail views illustratinganother aspect of making an example shielded electrical cable;

FIG. 8 a is a front cross-sectional view of another example embodimentof a shielded electrical cable, and FIG. 8 b is a corresponding detailview thereof;

FIG. 9 is a front cross-sectional view of a portion of another exampleshielded electrical cable;

FIG. 10 is a front cross-sectional view of a portion of another exampleshielded electrical cable;

FIGS. 11 a and 11 b are front cross-sectional views of two otherportions of example shielded electrical cables;

FIG. 12 is a graph comparing the electrical isolation performance of anexample shielded electrical cable to that of a conventional electricalcable;

FIG. 13 is a front cross-sectional view of another example shieldedelectrical cable;

FIG. 14 is a perspective view of an example shielded electrical ribboncable application;

FIGS. 15 and 16 are side views of bending/folding of an example cable;

FIG. 17 is a block diagram illustrating an example test setup formeasuring force versus deflection of a cable;

FIGS. 18 and 19 are graphs showing results of example force-deflectiontests for cables;

FIG. 20 is a logarithmic graph summarizing average values offorce-deflection tests for example cables;

FIG. 21 is a graph showing time domain reflectometer measurements ofdifferential impedance at a bend regions for a cable according to anexample embodiment; and

FIGS. 22-27 are side cross-sectional views of connectors according toexample embodiments.

In the figures, like reference numerals designate like elements.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings that form a part hereof, and in which is shown by way ofillustration various embodiments in which the invention may bepracticed. It is to be understood that other embodiments may beutilized, as structural and operational changes may be made withoutdeparting from the scope of the present invention. The followingdetailed description, therefore, is not to be taken in a limiting sense,and the scope of the invention is defined by the appended claims.

A growing number of applications require high speed (e.g., >1 Gb/s) highsignal integrity connections. These applications may include enterprisecomputing, network communication, factory automation, medical, test andinstrumentation, etc. These applications may use twin axial (“twinax”)transmission lines that include parallel pairs of differentially-drivenconductors. Each pair of conductors may be dedicated to a datatransmission channel. The construction of choice for these purposes isoften a jacketed loose bundle of shielded paired conductors. The jacketis often formed from shielding and/or insulating wrapped in a helicalpattern around the conductor bundle.

Applications are demanding more speed from these channels and morechannels per assembly. As a result, there will be a need for cables withimproved termination signal integrity, termination cost, impedance/skewcontrol, and cable cost over current twinax transmission lines. Thepresent disclosure is generally directed to a shielded electrical ribboncable that is suitable for, among other things, differentially drivenconductor sets. Due to the ribbon construction, the cable can readily beterminated to a printed circuit board connector of similar pitch. Such atermination can provide very high termination signal integrity. Theconstruction of this type of cable may generally include parallelinsulated wires that are bonded to a substrate on one or both sides withspecific placement of gaps between conductors. The substrates may or maynot contain a ground plane. Such a cable may be used as an alternativeto conventional bundled, e.g., differential pair, twin-axial (twinax)constructions and is expected to have lower cable cost, terminationcost, skew, and termination parasitics.

Shielded cables currently used in high performance and high speedapplications are generally not sharply bent because this may causeimpedance discontinuities at the bend location. Such discontinuities canproduce unwanted reflections and poor overall electrical performance.For example, a conventional parallel pair twinax cable for gigabit dataapplications may be constructed with an overlapped shield (helical wrap)and an outer layer of polymer film to maintain the wrapped shield inplace while bending. The wrapped layers add significant stiffness to thecable for bending, and also can cause pinching and local geometrychanges within the cable at the bend locations. This results insignificant changes in cable characteristics (e.g., impedance) at andproximate to the bend.

Compared to conventional, wrapped, parallel-pair, twinax cables, theribbon cable structures described in the present disclosure may exhibitimproved performance in applications that require sharp bending of thecable. These shield structures and cable constructions can maintain highcable electrical performance even after sharp bending. For example, suchribbon cables may be used with connectors that require the cable besharply bent within the connector. The constructions can also providemuch lower stiffness (e.g., up to one half) on bending than conventionalwrapped constructions with similar materials. The lower stiffness andminimal impact on electrical performance under bending allows suchcables to be bent more sharply than conventional cables, thereby savingspace and providing enhanced routability in a given application.

It is noted that the various sections and section headings are providedfor improved organization and convenience, and are not to be construedin a limiting way. For example, the sections and section headings arenot to be construed to mean that techniques, methods, features, orcomponents of one section cannot be used with techniques, methods,features, or components of a different section. On the contrary, weintend for any information from any given section or sections to also beapplicable to information in any other section or sections, unlessotherwise clearly indicated to the contrary.

Section 1: Shielded Electrical Cable Constructions and Features

As the number and speed of interconnected devices increases, electricalcables that carry signals between such devices need to be smaller andcapable of carrying higher speed signals without unacceptableinterference or crosstalk. Shielding is used in some electrical cablesto reduce interactions between signals carried by neighboringconductors. Many of the cables described herein have a generally flatconfiguration, and include conductor sets that extend along a length ofthe cable, as well as electrical shielding films disposed on oppositesides of the cable. Pinched portions of the shielding films betweenadjacent conductor sets help to electrically isolate the conductor setsfrom each other. Many of the cables also include drain wires thatelectrically connect to the shields, and extend along the length of thecable. The cable configurations described herein can help to simplifyconnections to the conductor sets and drain wires, reduce the size ofthe cable connection sites, and/or provide opportunities for masstermination of the cable.

In FIG. 1 an exemplary shielded electrical cable 2 is shown thatincludes a plurality of conductor sets 4 spaced apart from each otheralong all or a portion of a width, w, of the cable 2 and extend along alength, L, of the cable 2. The cable 2 may be arranged generally in aplanar configuration as illustrated in FIG. 1 or may be folded at one ormore places along its length into a folded configuration. In someimplementations, some parts of cable 2 may be arranged in a planarconfiguration and other parts of the cable may be folded. In someconfigurations, at least one of the conductor sets 4 of the cable 2includes two insulated conductors 6 extending along a length, L, ofcable 2. The two insulated conductors 6 of the conductor sets 4 may bearranged substantially parallel along all or a portion of the length, L,of the cable 2. Insulated conductors 6 may include insulated signalwires, insulated power wires, or insulated ground wires. Two shieldingfilms 8 are disposed on opposite sides of the cable 2.

The first and second shielding films 8 are arranged so that, intransverse cross section, cable 2 includes cover regions 14 and pinchedregions 18. In the cover regions 14 of the cable 2, cover portions 7 ofthe first and second shielding films 8 in transverse cross sectionsubstantially surround each conductor set 4. For example, cover portionsof the shielding films may collectively encompass at least 75%, or atleast 80, 85, or 90% of the perimeter of any given conductor set.Pinched portions 9 of the first and second shielding films form thepinched regions 18 of cable 2 on each side of each conductor set 4. Inthe pinched regions 18 of the cable 2, one or both of the shieldingfilms 8 are deflected, bringing the pinched portions 9 of the shieldingfilms 8 into closer proximity. In some configurations, as illustrated inFIG. 1, both of the shielding films 8 are deflected in the pinchedregions 18 to bring the pinched portions 9 into closer proximity. Insome configurations, one of the shielding films may remain relativelyflat in the pinched regions 18 when the cable is in a planar or unfoldedconfiguration, and the other shielding film on the opposite side of thecable may be deflected to bring the pinched portions of the shieldingfilm into closer proximity.

The cable 2 may also include an adhesive layer 10 disposed betweenshielding films 8 at least between the pinched portions 9. The adhesivelayer 10 bonds the pinched portions 9 of the shielding films 8 to eachother in the pinched regions 18 of the cable 2. The adhesive layer 10may or may not be present in the cover region 14 of the cable 2.

In some cases, conductor sets 4 have a substantiallycurvilinearly-shaped envelope or perimeter in transverse cross-section,and shielding films 8 are disposed around conductor sets 4 such as tosubstantially conform to and maintain the cross-sectional shape along atleast part of, and preferably along substantially all of, the length Lof the cable 6. Maintaining the cross-sectional shape maintains theelectrical characteristics of conductor sets 4 as intended in the designof conductor sets 4. This is an advantage over some conventionalshielded electrical cables where disposing a conductive shield around aconductor set changes the cross-sectional shape of the conductor set.

Although in the embodiment illustrated in FIG. 1, each conductor set 4has exactly two insulated conductors 6, in other embodiments, some orall of the conductor sets may include only one insulated conductor, ormay include more than two insulated conductors 6. For example, analternative shielded electrical cable similar in design to that of FIG.1 may include one conductor set that has eight insulated conductors 6,or eight conductor sets each having only one insulated conductor 6. Thisflexibility in arrangements of conductor sets and insulated conductorsallows the disclosed shielded electrical cables to be configured in waysthat are suitable for a wide variety of intended applications. Forexample, the conductor sets and insulated conductors may be configuredto form: a multiple twinaxial cable, i.e., multiple conductor sets eachhaving two insulated conductors; a multiple coaxial cable, i.e.,multiple conductor sets each having only one insulated conductor; orcombinations thereof. In some embodiments, a conductor set may furtherinclude a conductive shield (not shown) disposed around the one or moreinsulated conductors, and an insulative jacket (not shown) disposedaround the conductive shield.

In the embodiment illustrated in FIG. 1, shielded electrical cable 2further includes optional ground conductors 12. Ground conductors 12 mayinclude ground wires or drain wires. Ground conductors 12 can be spacedapart from and extend in substantially the same direction as insulatedconductors 6. Shielding films 8 can be disposed around ground conductors12. The adhesive layer 10 may bond shielding films 8 to each other inthe pinched portions 9 on both sides of ground conductors 12. Groundconductors 12 may electrically contact at least one of the shieldingfilms 8.

The cross-sectional views of FIGS. 2 a-2 g may represent variousshielded electrical cables, or portions of cables. In FIG. 2 a, shieldedelectrical cable 102 a includes a single conductor set 104. Conductorset 104 extends along the length of the cable and has only a singleinsulated conductor 106. If desired, the cable 102 a may be made toinclude multiple conductor sets 104 spaced apart from each other acrossa width of the cable 102 a and extending along a length of the cable.Two shielding films 108 are disposed on opposite sides of the cable. Thecable 102 a includes a cover region 114 and pinched regions 118. In thecover region 114 of the cable 102 a, the shielding films 108 includecover portions 107 that cover the conductor set 104. In transverse crosssection, the cover portions 107, in combination, substantially surroundthe conductor set 104. In the pinched regions 118 of the cable 102 a,the shielding films 108 include pinched portions 109 on each side of theconductor set 104.

An optional adhesive layer 110 may be disposed between shielding films108. Shielded electrical cable 102 a further includes optional groundconductors 112. Ground conductors 112 are spaced apart from and extendin substantially the same direction as insulated conductor 106.Conductor set 104 and ground conductors 112 can be arranged so that theylie generally in a plane as illustrated in FIG. 2 a.

Second cover portions 113 of shielding films 108 are disposed around,and cover, the ground conductors 112. The adhesive layer 110 may bondthe shielding films 108 to each other on both sides of ground conductors112. Ground conductors 112 may electrically contact at least one ofshielding films 108. In FIG. 2 a, insulated conductor 106 and shieldingfilms 108 are effectively arranged in a coaxial cable configuration. Thecoaxial cable configuration of FIG. 2 a can be used in a single endedcircuit arrangement.

As illustrated in the transverse cross sectional view of FIG. 2 a, thereis a maximum separation, D, between the cover portions 107 of theshielding films 108, and there is a minimum separation, d1, between thepinched portions 109 of the shielding films 108.

In FIG. 2 a, adhesive layer 110 is shown disposed between the pinchedportions 109 of the shielding films 108 in the pinched regions 118 ofthe cable 102 and disposed between the cover portions 107 of theshielding films 108 and the insulated conductor 106 in the cover region114 of the cable 102 a. In this arrangement, the adhesive layer 110bonds the pinched portions 109 of the shielding films 108 together inthe pinched regions 118 of the cable, and bonds the cover portions 107of the shielding films 108 to the insulated conductor 106 in the coverregion 114 of the cable 102 a.

Shielded cable 102 b of FIG. 2 b is similar to cable 102 a of FIG. 2 a,with similar elements identified by similar reference numerals, exceptthat in FIG. 2 b, the optional adhesive layer 110 b is not presentbetween the cover portions 107 of the shielding films 108 and theinsulated conductor 106 in the cover region 114 of the cable 102. Inthis arrangement, the adhesive layer 110 b bonds the pinched portions109 of the shielding films 108 together in the pinched regions 118 ofthe cable, but the adhesive layer 110 does not bond cover portions 107of the shielding films 108 to the insulated conductor 106 in the coverregions 114 of the cable 102.

Referring to FIG. 2 c, shielded electrical cable 102 c is similar toshielded electrical cable 102 a of FIG. 2 a, except that cable 102 c hasa single conductor set 104 c which has two insulated conductors 106 c.If desired, the cable 102 c may be made to include multiple conductorsets 104 c spaced part across a width of the cable 102 c and extendingalong a length of the cable. Insulated conductors 106 c are arrangedgenerally in a single plane and effectively in a twinaxialconfiguration. The twin axial cable configuration of FIG. 2 c can beused in a differential pair circuit arrangement or in a single endedcircuit arrangement.

Two shielding films 108 c are disposed on opposite sides of conductorset 104 c. The cable 102 c includes a cover region 114 c and pinchedregions 118 c. In the cover region 114 c of the cable 102 c, theshielding films 108 c include cover portions 107 c that cover theconductor set 104 c. In transverse cross section, the cover portions 107c, in combination, substantially surround the conductor set 104 c. Inthe pinched regions 118 c of the cable 102 c, the shielding films 108 cinclude pinched portions 109 c on each side of the conductor set 104 c.

An optional adhesive layer 110 c may be disposed between shielding films108 c. Shielded electrical cable 102 c further includes optional groundconductors 112 c similar to ground conductors 112 discussed previously.Ground conductors 112 c are spaced apart from, and extend insubstantially the same direction as, insulated conductors 106 c.Conductor set 104 c and ground conductors 112 c can be arranged so thatthey lie generally in a plane as illustrated in FIG. 2 c.

As illustrated in the cross section of FIG. 2 c, there is a maximumseparation, D, between the cover portions 107 c of the shielding films108 c; there is a minimum separation, d1, between the pinched portions109 c of the shielding films 108 c; and there is a minimum separation,d2, between the shielding films 108 c between the insulated conductors106 c.

FIG. 2 c shows the adhesive layer 110 c disposed between the pinchedportions 109 c of the shielding films 108 c in the pinched regions 118 cof the cable 102 c and disposed between the cover portions 107 c of theshielding films 108 c and the insulated conductors 106 c in the coverregion 114 c of the cable 102 c. In this arrangement, the adhesive layer110 c bonds the pinched portions 109 c of the shielding films 108 ctogether in the pinched regions 118 c of the cable 102 c, and also bondsthe cover portions 107 c of the shielding films 108 c to the insulatedconductors 106 c in the cover region 114 c of the cable 102 c.

Shielded cable 102 d of FIG. 2 d is similar to cable 102 c of FIG. 2 c,with similar elements identified by similar reference numerals, exceptthat in cable 102 d the optional adhesive layer 110 d is not presentbetween the cover portions 107 c of the shielding films 108 c and theinsulated conductors 106 c in the cover region 114 c of the cable. Inthis arrangement, the adhesive layer 110 d bonds the pinched portions109 c of the shielding films 108 c together in the pinched regions 118 cof the cable, but does not bond the cover portions 107 c of theshielding films 108 c to the insulated conductors 106 c in the coverregion 114 c of the cable 102 d.

Referring now to FIG. 2 e, we see there a transverse cross-sectionalview of a shielded electrical cable 102 e similar in many respects tothe shielded electrical cable 102 a of FIG. 2 a. However, where cable102 a includes a single conductor set 104 having only a single insulatedconductor 106, cable 102 e includes a single conductor set 104 e thathas two insulated conductors 106 e extending along a length of the cable102 e. Cable 102 e may be made to have multiple conductor sets 104 espaced apart from each other across a width of the cable 102 e andextending along a length of the cable 102 e. Insulated conductors 106 eare arranged effectively in a twisted pair cable arrangement, wherebyinsulated conductors 106 e twist around each other and extend along alength of the cable 102 e.

In FIG. 2 f another shielded electrical cable 102 f is shown that isalso similar in many respects to the shielded electrical cable 102 a ofFIG. 2 a. However, where cable 102 a includes a single conductor set 104having only a single insulated conductor 106, cable 102 f includes asingle conductor set 104 f that has four insulated conductors 106 fextending along a length of the cable 102 f. The cable 102 f may be madeto have multiple conductor sets 104 f spaced apart from each otheracross a width of the cable 102 f and extending along a length of thecable 102 f.

Insulated conductors 106 f are arranged effectively in a quad cablearrangement, whereby insulated conductors 106 f may or may not twistaround each other as insulated conductors 106 f extend along a length ofthe cable 102 f.

Referring back to FIGS. 2 a-2 f, further embodiments of shieldedelectrical cables may include a plurality of spaced apart conductor sets104, 104 c, 104 e, or 104 f, or combinations thereof, arranged generallyin a single plane. Optionally, the shielded electrical cables mayinclude a plurality of ground conductors 112 spaced apart from, andextending generally in the same direction as, the insulated conductorsof the conductor sets. In some configurations, the conductor sets andground conductors can be arranged generally in a single plane. FIG. 2 gillustrates an exemplary embodiment of such a shielded electrical cable.

Referring to FIG. 2 g, shielded electrical cable 102 g includes aplurality of spaced apart conductor sets 104, 104 c arranged generallyin plane. Shielded electrical cable 102 g further includes optionalground conductors 112 disposed between conductor sets 104, 104 c and atboth sides or edges of shielded electrical cable 102 g.

First and second shielding films 208 are disposed on opposite sides ofthe cable 102 g and are arranged so that, in transverse cross section,the cable 102 g includes cover regions 224 and pinched regions 228. Inthe cover regions 224 of the cable, cover portions 217 of the first andsecond shielding films 208 in transverse cross section substantiallysurround each conductor set 104, 104 c. Pinched portions 219 of thefirst and second shielding films 208 form the pinched regions 218 on twosides of each conductor set 104, 104 c.

The shielding films 208 are disposed around ground conductors 112. Anoptional adhesive layer 210 is disposed between shielding films 208 andbonds the pinched portions 219 of the shielding films 208 to each otherin the pinched regions 228 on both sides of each conductor set 104, 104c. Shielded electrical cable 102 g includes a combination of coaxialcable arrangements (conductor sets 104) and a twinaxial cablearrangement (conductor set 104 c) and may therefore be referred to as ahybrid cable arrangement.

One, two, or more of the shielded electrical cables may be terminated toa termination component such as a printed circuit board, paddle card, orthe like. Because the insulated conductors and ground conductors can bearranged generally in a single plane, the disclosed shielded electricalcables are well suited for mass-stripping, i.e., the simultaneousstripping of the shielding films and insulation from the insulatedconductors, and mass-termination, i.e., the simultaneous terminating ofthe stripped ends of the insulated conductors and ground conductors,which allows a more automated cable assembly process. This is anadvantage of at least some of the disclosed shielded electrical cables.The stripped ends of insulated conductors and ground conductors may, forexample, be terminated to contact conductive paths or other elements ona printed circuit board, for example. In other cases, the stripped endsof insulated conductors and ground conductors may be terminated to anysuitable individual contact elements of any suitable termination device,such as, e.g., electrical contacts of an electrical connector.

In FIGS. 3 a-3 d an exemplary termination process of shielded electricalcable 302 to a printed circuit board or other termination component 314is illustrated. This termination process can be a mass-terminationprocess and includes the steps of stripping (illustrated in FIGS. 3 a-3b), aligning (illustrated in FIG. 3 c), and terminating (illustrated inFIG. 3 d). When forming shielded electrical cable 302, which may ingeneral take the form of any of the cables shown and/or describedherein, the arrangement of conductor sets 304, insulated conductors 306,and ground conductors 312 of shielded electrical cable 302 may bematched to the arrangement of contact elements 316 on printed circuitboard 314, which would eliminate any significant manipulation of the endportions of shielded electrical cable 302 during alignment ortermination.

In the step illustrated in FIG. 3 a, an end portion 308 a of shieldingfilms 308 is removed. Any suitable method may be used, such as, e.g.,mechanical stripping or laser stripping. This step exposes an endportion of insulated conductors 306 and ground conductors 312. In oneaspect, mass-stripping of end portion 308 a of shielding films 308 ispossible because they form an integrally connected layer that isseparate from the insulation of insulated conductors 306. Removingshielding films 308 from insulated conductors 306 allows protectionagainst electrical shorting at these locations and also providesindependent movement of the exposed end portions of insulated conductors306 and ground conductors 312. In the step illustrated in FIG. 3 b, anend portion 306 a of the insulation of insulated conductors 306 isremoved. Any suitable method may be used, such as, e.g., mechanicalstripping or laser stripping. This step exposes an end portion of theconductor of insulated conductors 306. In the step illustrated in FIG. 3c, shielded electrical cable 302 is aligned with printed circuit board314 such that the end portions of the conductors of insulated conductors306 and the end portions of ground conductors 312 of shielded electricalcable 302 are aligned with contact elements 316 on printed circuit board314. In the step illustrated in FIG. 3 d, the end portions of theconductors of insulated conductors 306 and the end portions of groundconductors 312 of shielded electrical cable 302 are terminated tocontact elements 316 on printed circuit board 314. Examples of suitabletermination methods that may be used include soldering, welding,crimping, mechanical clamping, and adhesively bonding, to name a few.

In some cases, the disclosed shielded cables can be made to include oneor more longitudinal slits or other splits disposed between conductorsets. The splits may be used to separate individual conductor sets atleast along a portion of the length of shielded cable, therebyincreasing at least the lateral flexibility of the cable. This mayallow, for example, the shielded cable to be placed more easily into acurvilinear outer jacket. In other embodiments, splits may be placed soas to separate individual or multiple conductor sets and groundconductors. To maintain the spacing of conductor sets and groundconductors, splits may be discontinuous along the length of shieldedelectrical cable. To maintain the spacing of conductor sets and groundconductors in at least one end portion of a shielded electrical cable soas to maintain mass-termination capability, the splits may not extendinto one or both end portions of the cable. The splits may be formed inthe shielded electrical cable using any suitable method, such as, e.g.,laser cutting or punching. Instead of or in combination withlongitudinal splits, other suitable shapes of openings may be formed inthe disclosed shielded electrical cables, such as, e.g., holes, e.g., toincrease at least the lateral flexibility of the cable.

The shielding films used in the disclosed shielded cables can have avariety of configurations and be made in a variety of ways. In somecases, one or more shielding films may include a conductive layer and anon-conductive polymeric layer. The conductive layer may include anysuitable conductive material, including but not limited to copper,silver, aluminum, gold, and alloys thereof. The non-conductive polymericlayer may include any suitable polymeric material, including but notlimited to polyester, polyimide, polyamide-imide,polytetrafluoroethylene, polypropylene, polyethylene, polyphenylenesulfide, polyethylene naphthalate, polycarbonate, silicone rubber,ethylene propylene diene rubber, polyurethane, acrylates, silicones,natural rubber, epoxies, and synthetic rubber adhesive. Thenon-conductive polymeric layer may include one or more additives and/orfillers to provide properties suitable for the intended application. Insome cases, at least one of the shielding films may include a laminatingadhesive layer disposed between the conductive layer and thenon-conductive polymeric layer. For shielding films that have aconductive layer disposed on a non-conductive layer, or that otherwisehave one major exterior surface that is electrically conductive and anopposite major exterior surface that is substantially non-conductive,the shielding film may be incorporated into the shielded cable inseveral different orientations as desired. In some cases, for example,the conductive surface may face the conductor sets of insulated wiresand ground wires, and in some cases the non-conductive surface may facethose components. In cases where two shielding films are used onopposite sides of the cable, the films may be oriented such that theirconductive surfaces face each other and each face the conductor sets andground wires, or they may be oriented such that their non-conductivesurfaces face each other and each face the conductor sets and groundwires, or they may be oriented such that the conductive surface of oneshielding film faces the conductor sets and ground wires, while thenon-conductive surface of the other shielding film faces conductor setsand ground wires from the other side of the cable.

In some cases, at least one of the shielding films may be or include astand-alone conductive film, such as a compliant or flexible metal foil.The construction of the shielding films may be selected based on anumber of design parameters suitable for the intended application, suchas, e.g., flexibility, electrical performance, and configuration of theshielded electrical cable (such as, e.g., presence and location ofground conductors). In some cases, the shielding films may have anintegrally formed construction. In some cases, the shielding films mayhave a thickness in the range of 0.01 mm to 0.05 mm. The shielding filmsdesirably provide isolation, shielding, and precise spacing between theconductor sets, and allow for a more automated and lower cost cablemanufacturing process. In addition, the shielding films prevent aphenomenon known as “signal suck-out” or resonance, whereby high signalattenuation occurs at a particular frequency range. This phenomenontypically occurs in conventional shielded electrical cables where aconductive shield is wrapped around a conductor set.

As discussed elsewhere herein, adhesive material may be used in thecable construction to bond one or two shielding films to one, some, orall of the conductor sets at cover regions of the cable, and/or adhesivematerial may be used to bond two shielding films together at pinchedregions of the cable. A layer of adhesive material may be disposed on atleast one shielding film, and in cases where two shielding films areused on opposite sides of the cable, a layer of adhesive material may bedisposed on both shielding films. In the latter cases, the adhesive usedon one shielding film is preferably the same as, but may if desired bedifferent from, the adhesive used on the other shielding film. A givenadhesive layer may include an electrically insulative adhesive, and mayprovide an insulative bond between two shielding films. Furthermore, agiven adhesive layer may provide an insulative bond between at least oneof shielding films and insulated conductors of one, some, or all of theconductor sets, and between at least one of shielding films and one,some, or all of the ground conductors (if any). Alternatively, a givenadhesive layer may include an electrically conductive adhesive, and mayprovide a conductive bond between two shielding films. Furthermore, agiven adhesive layer may provide a conductive bond between at least oneof shielding films and one, some, or all of the ground conductors (ifany). Suitable conductive adhesives include conductive particles toprovide the flow of electrical current. The conductive particles can beany of the types of particles currently used, such as spheres, flakes,rods, cubes, amorphous, or other particle shapes. They may be solid orsubstantially solid particles such as carbon black, carbon fibers,nickel spheres, nickel coated copper spheres, metal-coated oxides,metal-coated polymer fibers, or other similar conductive particles.These conductive particles can be made from electrically insulatingmaterials that are plated or coated with a conductive material such assilver, aluminum, nickel, or indium tin-oxide. The metal-coatedinsulating material can be substantially hollow particles such as hollowglass spheres, or may comprise solid materials such as glass beads ormetal oxides. The conductive particles may be on the order of severaltens of microns to nanometer sized materials such as carbon nanotubes.Suitable conductive adhesives may also include a conductive polymericmatrix.

When used in a given cable construction, an adhesive layer is preferablysubstantially conformable in shape relative to other elements of thecable, and conformable with regard to bending motions of the cable. Insome cases, a given adhesive layer may be substantially continuous,e.g., extending along substantially the entire length and width of agiven major surface of a given shielding film. In some cases, theadhesive layer may include be substantially discontinuous. For example,the adhesive layer may be present only in some portions along the lengthor width of a given shielding film. A discontinuous adhesive layer mayfor example include a plurality of longitudinal adhesive stripes thatare disposed, e.g., between the pinched portions of the shielding filmson both sides of each conductor set and between the shielding filmsbeside the ground conductors (if any). A given adhesive material may beor include at least one of a pressure sensitive adhesive, a hot meltadhesive, a thermoset adhesive, and a curable adhesive. An adhesivelayer may be configured to provide a bond between shielding films thatis substantially stronger than a bond between one or more insulatedconductor and the shielding films. This may be achieved, e.g., byappropriate selection of the adhesive formulation. An advantage of thisadhesive configuration is to allow the shielding films to be readilystrippable from the insulation of insulated conductors. In other cases,an adhesive layer may be configured to provide a bond between shieldingfilms and a bond between one or more insulated conductor and theshielding films that are substantially equally strong. An advantage ofthis adhesive configuration is that the insulated conductors areanchored between the shielding films. When a shielded electrical cablehaving this construction is bent, this allows for little relativemovement and therefore reduces the likelihood of buckling of theshielding films. Suitable bond strengths may be chosen based on theintended application. In some cases, a conformable adhesive layer may beused that has a thickness of less than about 0.13 mm. In exemplaryembodiments, the adhesive layer has a thickness of less than about 0.05mm.

A given adhesive layer may conform to achieve desired mechanical andelectrical performance characteristics of the shielded electrical cable.For example, the adhesive layer may conform to be thinner between theshielding films in areas between conductor sets, which increases atleast the lateral flexibility of the shielded cable. This may allow theshielded cable to be placed more easily into a curvilinear outer jacket.In some cases, an adhesive layer may conform to be thicker in areasimmediately adjacent the conductor sets and substantially conform to theconductor sets. This may increase the mechanical strength and enableforming a curvilinear shape of shielding films in these areas, which mayincrease the durability of the shielded cable, for example, duringflexing of the cable. In addition, this may help to maintain theposition and spacing of the insulated conductors relative to theshielding films along the length of the shielded cable, which may resultin more uniform impedance and superior signal integrity of the shieldedcable.

A given adhesive layer may conform to effectively be partially orcompletely removed between the shielding films in areas betweenconductor sets, e.g., in pinched regions of the cable. As a result, theshielding films may electrically contact each other in these areas,which may increase the electrical performance of the cable. In somecases, an adhesive layer may conform to effectively be partially orcompletely removed between at least one of the shielding films and theground conductors. As a result, the ground conductors may electricallycontact at least one of shielding films in these areas, which mayincrease the electrical performance of the cable. Even in cases where athin layer of adhesive remains between at least one of shielding filmsand a given ground conductor, asperities on the ground conductor maybreak through the thin adhesive layer to establish electrical contact asintended.

In FIGS. 4 a-4 c, cross sectional views are shown of three exemplaryshielded electrical cables, which illustrate examples of the placementof ground conductors in the shielded electrical cables. An aspect of ashielded electrical cable is proper grounding of the shield, and suchgrounding can be accomplished in a number of ways. In some cases, agiven ground conductor can electrically contact at least one of theshielding films such that grounding the given ground conductor alsogrounds the shielding film or films. Such a ground conductor may also bereferred to as a “drain wire”. Electrical contact between the shieldingfilm and the ground conductor may be characterized by a relatively lowDC resistance, e.g., a DC resistance of less than 10 ohms, or less than2 ohms, or of substantially 0 ohms. In some cases, a given groundconductor may not electrically contact the shielding films, but may bean individual element in the cable construction that is independentlyterminated to any suitable individual contact element of any suitabletermination component, such as, e.g., a conductive path or other contactelement on a printed circuit board, paddle board, or other device. Sucha ground conductor may also be referred to as a “ground wire”. FIG. 4 aillustrates an exemplary shielded electrical cable in which groundconductors are positioned external to the shielding films. FIGS. 4 b and4 c illustrate embodiments in which the ground conductors are positionedbetween the shielding films, and may be included in the conductor set.One or more ground conductors may be placed in any suitable positionexternal to the shielding films, between the shielding films, or acombination of both.

Referring to FIG. 4 a, a shielded electrical cable 402 a includes asingle conductor set 404 a that extends along a length of the cable 402a. Conductor set 404 a has two insulated conductors 406, i.e., one pairof insulated conductors. Cable 402 a may be made to have multipleconductor sets 404 a spaced apart from each other across a width of thecable and extending along a length of the cable. Two shielding films 408a disposed on opposite sides of the cable include cover portions 407 a.In transverse cross section, the cover portions 407 a, in combination,substantially surround conductor set 404 a. An optional adhesive layer410 a is disposed between pinched portions 409 a of the shielding films408 a, and bonds shielding films 408 a to each other on both sides ofconductor set 404 a. Insulated conductors 406 are arranged generally ina single plane and effectively in a twinaxial cable configuration thatcan be used in a single ended circuit arrangement or a differential paircircuit arrangement. The shielded electrical cable 402 a furtherincludes a plurality of ground conductors 412 positioned external toshielding films 408 a. Ground conductors 412 are placed over, under, andon both sides of conductor set 404 a. Optionally, the cable 402 aincludes protective films 420 surrounding the shielding films 408 a andground conductors 412. Protective films 420 include a protective layer421 and an adhesive layer 422 bonding protective layer 421 to shieldingfilms 408 a and ground conductors 412. Alternatively, shielding films408 a and ground conductors 412 may be surrounded by an outer conductiveshield, such as, e.g., a conductive braid, and an outer insulativejacket (not shown).

Referring to FIG. 4 b, a shielded electrical cable 402 b includes asingle conductor set 404 b that extends along a length of cable 402 b.Conductor set 404 b has two insulated conductors 406, i.e., one pair ofinsulated conductors. Cable 402 b may be made to have multiple conductorsets 404 b spaced apart from each other across a width of the cable andextending along the length of the cable. Two shielding films 408 b aredisposed on opposite sides of the cable 402 b and include cover portions407 b. In transverse cross section, the cover portions 407 b, incombination, substantially surround conductor set 404 b. An optionaladhesive layer 410 b is disposed between pinched portions 409 b of theshielding films 408 b and bonds the shielding films to each other onboth sides of the conductor set. Insulated conductors 406 are arrangedgenerally in a single plane and effectively in a twinaxial ordifferential pair cable arrangement. Shielded electrical cable 402 bfurther includes a plurality of ground conductors 412 positioned betweenshielding films 408 b. Two of the ground conductors 412 are included inconductor set 404 b, and two of the ground conductors 412 are spacedapart from conductor set 404 b.

Referring to FIG. 4 c, a shielded electrical cable 402 c includes asingle conductor set 404 c that extends along a length of cable 402 c.Conductor set 404 c has two insulated conductors 406, i.e., one pair ofinsulated conductors. Cable 402 c may be made to have multiple conductorsets 404 c spaced apart from each other across a width of the cable andextending along the length of the cable. Two shielding films 408 c aredisposed on opposite sides of the cable 402 c and include cover portions407 c. In transverse cross section, the cover portions 407 c, incombination, substantially surround the conductor set 404 c. An optionaladhesive layer 410 c is disposed between pinched portions 409 c of theshielding films 408 c and bonds shielding films 408 c to each other onboth sides of conductor set 404 c. Insulated conductors 406 are arrangedgenerally in a single plane and effectively in a twinaxial ordifferential pair cable arrangement. Shielded electrical cable 402 cfurther includes a plurality of ground conductors 412 positioned betweenshielding films 408 c. All of the ground conductors 412 are included inthe conductor set 404 c. Two of the ground conductors 412 and insulatedconductors 406 are arranged generally in a single plane.

The disclosed shielded cables can, if desired, be connected to a circuitboard or other termination component using one or more electricallyconductive cable clips. For example, a shielded electrical cable mayinclude a plurality of spaced apart conductor sets arranged generally ina single plane, and each conductor set may include two insulatedconductors that extend along a length of the cable. Two shielding filmsmay be disposed on opposite sides of the cable and, in transverse crosssection, substantially surround each of the conductor sets. A cable clipmay be clamped or otherwise attached to an end portion of the shieldedelectrical cable such that at least one of shielding films electricallycontacts the cable clip. The cable clip may be configured fortermination to a ground reference, such as, e.g., a conductive trace orother contact element on a printed circuit board, to establish a groundconnection between shielded electrical cable and the ground reference.The cable clip may be terminated to the ground reference using anysuitable method, including soldering, welding, crimping, mechanicalclamping, and adhesively bonding, to name a few. When terminated, thecable clip may facilitate termination of end portions of the conductorsof the insulated conductors of the shielded electrical cable to contactelements of a termination point, such as, e.g., contact elements onprinted circuit board. The shielded electrical cable may include one ormore ground conductors as described herein that may electrically contactthe cable clip in addition to or instead of at least one of theshielding films.

In FIGS. 5 a-5 c an exemplary method of making a shielded electricalcable is illustrated. Specifically, these figures illustrate anexemplary method of making a shielded electrical cable that may besubstantially the same as that shown in FIG. 1. In the step illustratedin FIG. 5 a, insulated conductors 506 are formed using any suitablemethod, such as, e.g., extrusion, or are otherwise provided. Insulatedconductors 506 may be formed of any suitable length. Insulatedconductors 506 may then be provided as such or cut to a desired length.Ground conductors 512 (see FIG. 5 c) may be formed and provided in asimilar fashion.

In the step illustrated in FIG. 5 b, shielding films 508 are formed. Asingle layer or multilayer web may be formed using any suitable method,such as, e.g., continuous wide web processing. Shielding films 508 maybe formed of any suitable length. Shielding films 508 may then beprovided as such or cut to a desired length and/or width. Shieldingfilms 508 may be pre-formed to have transverse partial folds to increaseflexibility in the longitudinal direction. One or both of the shieldingfilms may include a conformable adhesive layer 510, which may be formedon the shielding films 508 using any suitable method, such as, e.g.,laminating or sputtering.

In the step illustrated in FIG. 5 c, a plurality of insulated conductors506, ground conductors 512, and shielding films 508 are provided. Aforming tool 524 is provided. Forming tool 524 includes a pair offorming rolls 526 a, 526 b having a shape corresponding to a desiredcross-sectional shape of the finished shielded electrical cable, theforming tool also including a bite 528. Insulated conductors 506, groundconductors 512, and shielding films 508 are arranged according to theconfiguration of the desired shielded cable, such as any of the cablesshown and/or described herein, and positioned in proximity to formingrolls 526 a, 526 b, after which they are concurrently fed into bite 528of forming rolls 526 a, 526 b and disposed between forming rolls 526 a,526 b. The forming tool 524 forms shielding films 508 around conductorsets 504 and ground conductor 512 and bonds shielding films 508 to eachother on both sides of each conductor set 504 and ground conductors 512.Heat may be applied to facilitate bonding. Although in this embodiment,forming shielding films 508 around conductor sets 504 and groundconductor 512 and bonding shielding films 508 to each other on bothsides of each conductor set 504 and ground conductors 512 occur in asingle operation, in other embodiments, these steps may occur inseparate operations.

In subsequent fabrication operations, longitudinal splits may if desiredbe formed between the conductor sets. Such splits may be formed in theshielded cable using any suitable method, such as, e.g., laser cuttingor punching. In another optional fabrication operation, the shieldedelectrical cable may be folded lengthwise along the pinched regionsmultiple times into a bundle, and an outer conductive shield may beprovided around the folded bundle using any suitable method. An outerjacket may also be provided around the outer conductive shield using anysuitable method, such as, e.g., extrusion. In other embodiments, theouter conductive shield may be omitted and the outer jacket may beprovided by itself around the folded shielded cable.

In FIGS. 6 a-6 c a detail of an exemplary method of making a shieldedelectrical cable is illustrated. In particular, these figures illustratehow one or more adhesive layers may be conformably shaped during theforming and bonding of the shielding films. In the step illustrated inFIG. 6 a, an insulated conductor 606, a ground conductor 612 spacedapart from the insulated conductor 606, and two shielding films 608 areprovided. Shielding films 608 each include a conformable adhesive layer610. In the steps illustrated in FIGS. 6 b-6 c, shielding films 608 areformed around insulated conductor 606 and ground conductor 612 andbonded to each other. Initially, as illustrated in FIG. 6 b, theadhesive layers 610 still have their original thickness. As the formingand bonding of shielding films 608 proceeds, the adhesive layers 610conform to achieve desired mechanical and electrical performancecharacteristics of finished shielded electrical cable 602 (FIG. 6 c).

As illustrated in FIG. 11 c, adhesive layers 610 conform to be thinnerbetween shielding films 608 on both sides of insulated conductor 606 andground conductor 612; a portion of adhesive layers 610 displaces awayfrom these areas. Further, adhesive layers 610 conform to be thicker inareas immediately adjacent insulated conductor 606 and ground conductor612, and substantially conform to insulated conductor 606 and groundconductor 612; a portion of adhesive layers 610 displaces into theseareas. Further, adhesive layers 610 conform to effectively be removedbetween shielding films 608 and ground conductor 612; the adhesivelayers 610 displace away from these areas such that ground conductor 612electrically contacts shielding films 608.

Shown in FIGS. 7 a and 7 b are details pertaining to a pinched regionduring the manufacture of an exemplary shielded electrical cable.Shielded electrical cable 702 (see FIG. 7 b) is made using two shieldingfilms 708 and includes a pinched region 718 (see FIG. 7 b) whereinshielding films 708 may be substantially parallel. Shielding films 708include a non-conductive polymeric layer 708 b, a conductive layer 708 adisposed on non-conductive polymeric layer 708 b, and a stop layer 708 ddisposed on the conductive layer 708 a. A conformable adhesive layer 710is disposed on stop layer 708 d. Pinched region 718 includes alongitudinal ground conductor 712 disposed between shielding films 708.After the shielding films are forced together around the groundconductor, the ground conductor 712 makes indirect electrical contactwith the conductive layers 708 a of shielding films 708. This indirectelectrical contact is enabled by a controlled separation of conductivelayer 708 a and ground conductor 712 provided by stop layer 708 d. Insome cases, the stop layer 708 d may be or include a non-conductivepolymeric layer. As shown in the figures, an external pressure (see FIG.17 a) is used to press conductive layers 708 a together and force theadhesive layers 710 to conform around the ground conductor 712 (FIG. 17b). Because the stop layer 708 d does not conform at least under thesame processing conditions, it prevents direct electrical contactbetween the ground conductor 712 and conductive layer 708 a of theshielding films 708, but achieves indirect electrical contact. Thethickness and dielectric properties of stop layer 708 d may be selectedto achieve a low target DC resistance, i.e., electrical contact of anindirect type. In some embodiments, the characteristic DC resistancebetween the ground conductor and the shielding film may be less than 10ohms, or less than 5 ohms, for example, but greater than 0 ohms, toachieve the desired indirect electrical contact. In some cases, it isdesirable to make direct electrical contact between a given groundconductor and one or two shielding films, whereupon the DC resistancebetween such ground conductor and such shielding film(s) may besubstantially 0 ohms.

In exemplary embodiments, the cover regions of the shielded electricalcable include concentric regions and transition regions positioned onone or both sides of a given conductor set. Portions of a givenshielding film in the concentric regions are referred to as concentricportions of the shielding film, and portions of the shielding film inthe transition regions are referred to as transition portions of theshielding film. The transition regions can be configured to provide highmanufacturability and strain and stress relief of the shieldedelectrical cable. Maintaining the transition regions at a substantiallyconstant configuration (including aspects such as, e.g., size, shape,content, and radius of curvature) along the length of the shieldedelectrical cable may help the shielded electrical cable to havesubstantially uniform electrical properties, such as, e.g., highfrequency isolation, impedance, skew, insertion loss, reflection, modeconversion, eye opening, and jitter.

Additionally, in certain embodiments, such as, e.g., embodiments whereinthe conductor set includes two insulated conductors that extend along alength of the cable that are arranged generally in a single andeffectively as a twinaxial cable that can be connected in a differentialpair circuit arrangement, maintaining the transition portion at asubstantially constant configuration along the length of the shieldedelectrical cable can beneficially provide substantially the sameelectromagnetic field deviation from an ideal concentric case for bothconductors in the conductor set. Thus, careful control of theconfiguration of this transition portion along the length of theshielded electrical cable can contribute to the advantageous electricalperformance and characteristics of the cable. FIGS. 8 a through 10illustrate various exemplary embodiments of a shielded electrical cablethat include transition regions of the shielding films disposed on oneor both sides of the conductor set.

The shielded electrical cable 802, which is shown in cross section inFIGS. 8 a and 8 b, includes a single conductor set 804 that extendsalong a length of the cable. The cable 802 may be made to have multipleconductor sets 804 spaced apart from each other along a width of thecable and extending along a length of the cable. Although only oneinsulated conductor 806 is shown in FIG. 8 a, multiple insulatedconductors may be included in the conductor set 804 if desired.

The insulated conductor of a conductor set that is positioned nearest toa pinched region of the cable is considered to be an end conductor ofthe conductor set. The conductor set 804, as shown, has a singleinsulated conductor 806, and it is also an end conductor since it ispositioned nearest to the pinched region 818 of the shielded electricalcable 802.

First and second shielding films 808 are disposed on opposite sides ofthe cable and include cover portions 807. In transverse cross section,the cover portions 807 substantially surround conductor set 804. Anoptional adhesive layer 810 is disposed between the pinched portions 809of the shielding films 808, and bonds shielding films 808 to each otherin the pinched regions 818 of the cable 802 on both sides of conductorset 804. The optional adhesive layer 810 may extend partially or fullyacross the cover portion 807 of the shielding films 808, e.g., from thepinched portion 809 of the shielding film 808 on one side of theconductor set 804 to the pinched portion 809 of the shielding film 808on the other side of the conductor set 804.

Insulated conductor 806 is effectively arranged as a coaxial cable whichmay be used in a single ended circuit arrangement. Shielding films 808may include a conductive layer 808 a and a non-conductive polymericlayer 808 b. In some embodiments, as illustrated by FIGS. 8 a and 8 b,the conductive layer 808 a of both shielding films faces the insulatedconductors. Alternatively, the orientation of the conductive layers ofone or both of shielding films 808 may be reversed, as discussedelsewhere herein.

Shielding films 808 include a concentric portion that is substantiallyconcentric with the end conductor 806 of the conductor set 804. Theshielded electrical cable 802 includes transition regions 836. Portionsof the shielding film 808 in the transition region 836 of the cable 802are transition portions 834 of the shielding films 808. In someembodiments, shielded electrical cable 802 includes a transition region836 positioned on both sides of the conductor set 804, and in someembodiments a transition region 836 may be positioned on only one sideof conductor set 804.

Transition regions 836 are defined by shielding films 808 and conductorset 804. The transition portions 834 of the shielding films 808 in thetransition regions 836 provide a gradual transition between concentricportions 811 and pinched portions 809 of the shielding films 808. Asopposed to a sharp transition, such as, e.g., a right-angle transitionor a transition point (as opposed to a transition portion), a gradual orsmooth transition, such as, e.g., a substantially sigmoidal transition,provides strain and stress relief for shielding films 808 in transitionregions 836 and prevents damage to shielding films 808 when shieldedelectrical cable 802 is in use, e.g., when laterally or axially bendingshielded electrical cable 802. This damage may include, e.g., fracturesin conductive layer 808 a and/or debonding between conductive layer 808a and non-conductive polymeric layer 808 b. In addition, a gradualtransition prevents damage to shielding films 808 in manufacturing ofshielded electrical cable 802, which may include, e.g., cracking orshearing of conductive layer 808 a and/or non-conductive polymeric layer808 b. Use of the disclosed transition regions on one or both sides ofone, some, or all of the conductor sets in a shielded electrical ribboncable represents a departure from conventional cable configurations,such as, e.g., a typical coaxial cable, wherein a shield is generallycontinuously disposed around a single insulated conductor, or a typicalconventional twinaxial cable in which a shield is continuously disposedaround a pair of insulated conductors. Although these conventionalshielding configurations may provide model electromagnetic profiles,such profiles may not be necessary to achieve acceptable electricalproperties in a given application.

According to one aspect of at least some of the disclosed shieldedelectrical cables, acceptable electrical properties can be achieved byreducing the electrical impact of the transition region, e.g., byreducing the size of the transition region and/or carefully controllingthe configuration of the transition region along the length of theshielded electrical cable. Reducing the size of the transition regionreduces the capacitance deviation and reduces the required space betweenmultiple conductor sets, thereby reducing the conductor set pitch and/orincreasing the electrical isolation between conductor sets. Carefulcontrol of the configuration of the transition region along the lengthof the shielded electrical cable contributes to obtaining predictableelectrical behavior and consistency, which provides for high speedtransmission lines so that electrical data can be more reliablytransmitted. Careful control of the configuration of the transitionregion along the length of the shielded electrical cable is a factor asthe size of the transition portion approaches a lower size limit.

An electrical characteristic that is often considered is thecharacteristic impedance of the transmission line. Any impedance changesalong the length of a transmission line may cause power to be reflectedback to the source instead of being transmitted to the target. Ideally,the transmission line will have no impedance variation along its length,but, depending on the intended application, variations up to 5-10% maybe acceptable. Another electrical characteristic that is oftenconsidered in twinaxial cables (differentially driven) is skew orunequal transmission speeds of two transmission lines of a pair along atleast a portion of their length. Skew produces conversion of thedifferential signal to a common mode signal that can be reflected backto the source, reduces the transmitted signal strength, createselectromagnetic radiation, and can dramatically increase the bit errorrate, in particular jitter. Ideally, a pair of transmission lines willhave no skew, but, depending on the intended application, a differentialS-parameter SCD21 or SCD12 value (representing the differential-tocommon mode conversion from one end of the transmission line to theother) of less than −25 to −30 dB up to a frequency of interest, suchas, e.g., 6 GHz, may be acceptable. Alternatively, skew can be measuredin the time domain and compared to a required specification. Dependingon the intended application, values of less than about 20picoseconds/meter (ps/m) and preferably less than about 10 ps/m may beacceptable.

Referring again to FIGS. 8 a and 8 b, in part to help achieve acceptableelectrical properties, transition regions 836 of shielded electricalcable 802 may each include a cross-sectional transition area 836 a. Thetransition area 836 a is preferably smaller than a cross-sectional area806 a of conductor 806. As best shown in FIG. 8 b, cross-sectionaltransition area 836 a of transition region 836 is defined by transitionpoints 834′ and 834″.

The transition points 834′ occur where the shielding films deviate frombeing substantially concentric with the end insulated conductor 806 ofthe conductor set 804. The transition points 834′ are the points ofinflection of the shielding films 808 at which the curvature of theshielding films 808 changes sign. For example, with reference to FIG. 8b, the curvature of the upper shielding film 808 transitions fromconcave downward to concave upward at the inflection point which is theupper transition point 834′ in the figure. The curvature of the lowershielding film 808 transitions from concave upward to concave downwardat the inflection point which is the lower transition point 834′ in thefigure. The other transition points 834″ occur where a separationbetween the pinched portions 809 of the shielding films 808 exceeds theminimum separation d1 of the pinched portions 809 by a predeterminedfactor, e.g., 1.2 or 1.5.

In addition, each transition area 836 a may include a void area 836 b.Void areas 836 b on either side of the conductor set 804 may besubstantially the same. Further, adhesive layer 810 may have a thicknessTac at the concentric portion 811 of the shielding film 808, and athickness at the transition portion 834 of the shielding film 808 thatis greater than thickness Tac. Similarly, adhesive layer 810 may have athickness Tap between the pinched portions 809 of the shielding films808, and a thickness at the transition portion 834 of the shielding film808 that is greater than thickness Tap. Adhesive layer 810 may representat least 25% of cross-sectional transition area 836 a. The presence ofadhesive layer 810 in transition area 836 a, in particular at athickness that is greater than thickness Tac or thickness Tap,contributes to the strength of the cable 802 in the transition region836.

Careful control of the manufacturing process and the materialcharacteristics of the various elements of shielded electrical cable 802may reduce variations in void area 836 b and the thickness ofconformable adhesive layer 810 in transition region 836, which may inturn reduce variations in the capacitance of cross-sectional transitionarea 836 a. Shielded electrical cable 802 may include transition region836 positioned on one or both sides of conductor set 804 that includes across-sectional transition area 836 a that is substantially equal to orsmaller than a cross-sectional area 806 a of conductor 806. Shieldedelectrical cable 802 may include a transition region 836 positioned onone or both sides of conductor set 804 that includes a cross-sectionaltransition area 836 a that is substantially the same along the length ofconductor 806. For example, cross-sectional transition area 836 a mayvary less than 50% over a length of 1 meter. Shielded electrical cable802 may include transition regions 836 positioned on both sides ofconductor set 804 that each include a cross-sectional transition area,wherein the sum of cross-sectional areas 834 a is substantially the samealong the length of conductor 806. For example, the sum ofcross-sectional areas 834 a may vary less than 50% over a length of 1 m.Shielded electrical cable 802 may include transition regions 836positioned on both sides of conductor set 804 that each include across-sectional transition area 836 a, wherein the cross-sectionaltransition areas 836 a are substantially the same. Shielded electricalcable 802 may include transition regions 836 positioned on both sides ofconductor set 804, wherein the transition regions 836 are substantiallyidentical. Insulated conductor 806 has an insulation thickness Ti, andtransition region 836 may have a lateral length Lt that is less thaninsulation thickness Ti. The central conductor of insulated conductor806 has a diameter Dc, and transition region 836 may have a laterallength Lt that is less than the diameter Dc. The various configurationsdescribed above may provide a characteristic impedance that remainswithin a desired range, such as, e.g., within 5-10% of a targetimpedance value, such as, e.g., 50 ohms, over a given length, such as,e.g., 1 meter.

Factors that can influence the configuration of transition region 836along the length of shielded electrical cable 802 include themanufacturing process, the thickness of conductive layers 808 a andnon-conductive polymeric layers 808 b, adhesive layer 810, and the bondstrength between insulated conductor 806 and shielding films 808, toname a few.

In one aspect, conductor set 804, shielding films 808, and transitionregion 836 may be cooperatively configured in an impedance controllingrelationship. An impedance controlling relationship means that conductorset 804, shielding films 808, and transition region 836 arecooperatively configured to control the characteristic impedance of theshielded electrical cable.

In FIG. 9 an exemplary shielded electrical cable 902 is shown, intransverse cross section, that includes two insulated conductors in aconnector set 904, the individually insulated conductors 906 eachextending along a length of the cable 902. Two shielding films 908 aredisposed on opposite sides of the cable 902 and in combinationsubstantially surround conductor set 904. An optional adhesive layer 910is disposed between pinched portions 909 of the shielding films 908 andbonds shielding films 908 to each other on both sides of conductor set904 in the pinched regions 918 of the cable. Insulated conductors 906can be arranged generally in a single plane and effectively in atwinaxial cable configuration. The twinaxial cable configuration can beused in a differential pair circuit arrangement or in a single endedcircuit arrangement. Shielding films 908 may include a conductive layer908 a and a non-conductive polymeric layer 908 b, or may include theconductive layer 908 a without the non-conductive polymeric layer 908 b.In the figure, the conductive layer 908 a of each shielding film isshown facing insulated conductors 906, but in alternative embodiments,one or both of the shielding films may have a reversed orientation.

The cover portion 907 of at least one of the shielding films 908includes concentric portions 911 that are substantially concentric withcorresponding end conductors 906 of the conductor set 904. In thetransition regions of the cable 902, transition portion 934 of theshielding films 908 are between the concentric portions 911 and thepinched portions 909 of the shielding films 908. Transition portions 934are positioned on both sides of conductor set 904, and each such portionincludes a cross-sectional transition area 934 a. The sum ofcross-sectional transition areas 934 a is preferably substantially thesame along the length of conductors 906. For example, the sum ofcross-sectional areas 934 a may vary less than 50% over a length of 1 m.

In addition, the two cross-sectional transition areas 934 a may besubstantially the same and/or substantially identical. Thisconfiguration of transition regions contributes to a characteristicimpedance for each conductor 906 (single-ended) and a differentialimpedance that both remain within a desired range, such as, e.g., within5-10% of a target impedance value over a given length, such as, e.g., 1m. In addition, this configuration of the transition regions mayminimize skew of the two conductors 906 along at least a portion oftheir length.

When the cable is in an unfolded, planar configuration, each of theshielding films may be characterizable in transverse cross section by aradius of curvature that changes across a width of the cable 902. Themaximum radius of curvature of the shielding film 908 may occur, forexample, at the pinched portion 909 of the cable 902, or near the centerpoint of the cover portion 907 of the multi-conductor cable set 904illustrated in FIG. 9. At these positions, the film may be substantiallyflat and the radius of curvature may be substantially infinite. Theminimum radius of curvature of the shielding film 908 may occur, forexample, at the transition portion 934 of the shielding film 908. Insome embodiments, the radius of curvature of the shielding film acrossthe width of the cable is at least about 50 micrometers, i.e., theradius of curvature does not have a magnitude smaller than 50micrometers at any point along the width of the cable, between the edgesof the cable. In some embodiments, for shielding films that include atransition portion, the radius of curvature of the transition portion ofthe shielding film is similarly at least about 50 micrometers.

In an unfolded, planar configuration, shielding films that include aconcentric portion and a transition portion are characterizable by aradius of curvature of the concentric portion, R1, and/or a radius ofcurvature of the transition portion r1. These parameters are illustratedin FIG. 9 for the cable 902. In exemplary embodiments, R1/r1 is in arange of 2 to 15.

In FIG. 10 another exemplary shielded electrical cable 1002 isillustrated which includes a conductor set having two insulatedconductors 1006. In this embodiment, the shielding films 1008 have anasymmetric configuration, which changes the position of the transitionportions relative to a more symmetric embodiment such as that of FIG. 9.In FIG. 10, shielded electrical cable 1002 has pinched portions 1009 ofshielding films 1008 that lie in a plane that is slightly offset fromthe plane of symmetry of the insulated conductors 1006. Despite theslight offset, the cable of FIG. 10 and its various elements can stillbe considered to extend generally along a given plane and to besubstantially planar. The transition regions 1036 have a somewhat offsetposition and configuration relative to other depicted embodiments.However, by ensuring that the two transition regions 1036 are positionedsubstantially symmetrically with respect to corresponding insulatedconductors 1006 (e.g. with respect to a vertical plane between theconductors 1006), and that the configuration of transition regions 1036is carefully controlled along the length of shielded electrical cable1002, the shielded electrical cable 1002 can be configured to stillprovide acceptable electrical properties.

In FIGS. 11 a and 11 b additional exemplary shielded electrical cablesare illustrated. These figures are used to further explain how a pinchedportion of the cable is configured to electrically isolate a conductorset of the shielded electrical cable. The conductor set may beelectrically isolated from an adjacent conductor set (e.g., to minimizecrosstalk between adjacent conductor sets) or from the externalenvironment of the shielded electrical cable (e.g., to minimizeelectromagnetic radiation escape from the shielded electrical cable andminimize electromagnetic interference from external sources). In bothcases, the pinched portion may include various mechanical structures torealize the electrical isolation. Examples include close proximity ofthe shielding films, high dielectric constant material between theshielding films, ground conductors that make direct or indirectelectrical contact with at least one of the shielding films, extendeddistance between adjacent conductor sets, physical breaks betweenadjacent conductor sets, intermittent contact of the shielding films toeach other directly either longitudinally, transversely, or both, andconductive adhesive, to name a few.

Shown in FIG. 11 a, in cross section, is a shielded electrical cable1102 that includes two conductor sets 1104 a, 104 b spaced apart acrossa width of the cable 102 and extending longitudinally along a length ofthe cable. Each conductor set 1104 a, 1104 b has two insulatedconductors 1106 a, 1106 b. Two shielding films 1108 are disposed onopposite sides of the cable 1102. In transverse cross section, coverportions 1107 of the shielding films 1108 substantially surroundconductor sets 1104 a, 1104 b in cover regions 1114 of the cable 1102.In pinched regions 1118 of the cable, on both sides of the conductorsets 1104 a, 1104 b, the shielding films 1108 include pinched portions1109. In shielded electrical cable 1102, the pinched portions 1109 ofshielding films 1108 and insulated conductors 1106 are arrangedgenerally in a single plane when the cable 1102 is in a planar and/orunfolded arrangement. Pinched portions 1109 positioned in betweenconductor sets 1104 a, 1104 b are configured to electrically isolateconductor sets 1104 a, 1104 b from each other. When arranged in agenerally planar, unfolded arrangement, as illustrated in FIG. 11 a, thehigh frequency electrical isolation of the first insulated conductor1106 a in the conductor set 1104 a relative to the second insulatedconductor 1106 b in the conductor set 1104 a is substantially less thanthe high frequency electrical isolation of the first conductor set 1104a relative to the second conductor set 1104 b.

As illustrated in the cross section of FIG. 11 a, the cable 1102 can becharacterized by a maximum separation, D, between the cover portions1107 of the shielding films 1108, a minimum separation, d2, between thecover portions 1107 of the shielding films 1108, and a minimumseparation, d1, between the pinched portions 1109 of the shielding films1108. In some embodiments, d1/D is less than 0.25, or less than 0.1. Insome embodiments, d2/D is greater than 0.33.

An optional adhesive layer may be included as shown between the pinchedportions 1109 of the shielding films 1108. The adhesive layer may becontinuous or discontinuous. In some embodiments, the adhesive layer mayextend fully or partially in the cover region 1114 of the cable 1102,e.g., between the cover portion 1107 of the shielding films 1108 and theinsulated conductors 1106 a, 1106 b. The adhesive layer may be disposedon the cover portion 1107 of the shielding film 1108 and may extendfully or partially from the pinched portion 1109 of the shielding film1108 on one side of a conductor set 1104 a, 1104 b to the pinchedportion 1109 of the shielding film 1108 on the other side of theconductor set 1104 a, 1104 b.

The shielding films 1108 can be characterized by a radius of curvature,R, across a width of the cable 1102 and/or by a radius of curvature, r1,of the transition portion 1112 of the shielding film and/or by a radiusof curvature, r2, of the concentric portion 1111 of the shielding film.

In the transition region 1136, the transition portion 1112 of theshielding film 1108 can be arranged to provide a gradual transitionbetween the concentric portion 1111 of the shielding film 1108 and thepinched portion 1109 of the shielding film 1108. The transition portion1112 of the shielding film 1108 extends from a first transition point1121, which is the inflection point of the shielding film 1108 and marksthe end of the concentric portion 1111, to a second transition point1122 where the separation between the shielding films exceeds theminimum separation, d1, of the pinched portions 1109 by a predeterminedfactor.

In some embodiments, the cable 1102 includes at least one shielding filmthat has a radius of curvature, R, across the width of the cable that isat least about 50 micrometers and/or the minimum radius of curvature,r1, of the transition portion 1112 of the shielding film 1102 is atleast about 50 micrometers. In some embodiments, the ratio of theminimum radius of curvature of the concentric portion to the minimumradius of curvature of the transition portion, r2/r1 is in a range of 2to 15.

In FIG. 11 b is a cross sectional view of a shielded electrical cable1202 that includes two conductor sets 1204 spaced apart from each otheracross a width of the cable and extending longitudinally along a lengthof the cable. Each conductor set 1204 has only one insulated conductor1206, and two shielding films 1208 are disposed on opposite sides of thecable 1202. In transverse cross section, the cover portions 1207 of theshielding films 1208 in combination substantially surround the insulatedconductor 1206 of conductor sets 1204 in a cover region 1214 of thecable. In pinched regions 1218 of the cable, on both sides of theconductor sets 1204, the shielding films 1208 include pinched portions1209. In shielded electrical cable 1202, pinched portions 1209 ofshielding films 1208 and insulated conductors 1206 can be arrangedgenerally in a single plane when the cable 1202 is in a planar and/orunfolded arrangement. The cover portions 1207 of the shielding films1208 and/or the pinched regions 1218 of the cable 1202 are configured toelectrically isolate the conductor sets 1204 from each other.

As shown in the figure, the cable 1202 can be characterized by a maximumseparation, D, between the cover portions 1207 of the shielding films1208, and a minimum separation, d1, between the pinched portions 1209 ofthe shielding films 1208. In exemplary embodiments, d1/D is less than0.25, or less than 0.1.

An optional adhesive layer may be disposed as shown between the pinchedportions 1209 of the shielding films 1208. The adhesive layer may becontinuous or discontinuous. In some embodiments, the adhesive layer mayextend fully or partially in the cover region 1214 of the cable, e.g.,between the cover portions 1207 of the shielding films 1208 and theinsulated conductors 1206. The adhesive layer may be disposed on thecover portions 1207 of the shielding films 1208 and may extend fully orpartially from the pinched portions 1209 of the shielding films 1208 onone side of a conductor set 1204 to the pinched portions 1209 of theshielding films 1208 on the other side of the conductor set 1204.

The shielding films 1208 can be characterized by a radius of curvature,R, across a width of the cable 1202 and/or by a minimum radius ofcurvature, r1, in the transition portion 1212 of the shielding film 1208and/or by a minimum radius of curvature, r2, of the concentric portion1211 of the shielding film 1208. In the transition regions 1236 of thecable 1202, transition portions 1212 of the shielding films 1202 can beconfigured to provide a gradual transition between the concentricportions 1211 of the shielding films 1208 and the pinched portions 1209of the shielding films 1208. The transition portion 1212 of theshielding film 1208 extends from a first transition point 1221, which isthe inflection point of the shielding film 1208 and marks the end of theconcentric portion 1211, to a second transition point 1222 where theseparation between the shielding films exceeds the minimum separation,d1, of the pinched portions 1209 by a predetermined factor.

In some embodiments, the radius of curvature, R, of the shielding filmacross the width of the cable is at least about 50 micrometers and/orthe minimum radius of curvature in the transition portion of theshielding film is at least 50 micrometers.

In some cases, the pinched regions of any of the described shieldedcables can be configured to be laterally bent at an angle α of at least30°, for example. This lateral flexibility of the pinched regions canenable the shielded cable to be folded in any suitable configuration,such as, e.g., a configuration that can be used in a round cable. Insome cases, the lateral flexibility of the pinched regions is enabled byshielding films that include two or more relatively thin individuallayers. To warrant the integrity of these individual layers inparticular under bending conditions, it is preferred that the bondsbetween them remain intact. The pinched regions may for example have aminimum thickness of less than about 0.13 mm, and the bond strengthbetween individual layers may be at least 17.86 g/mm (1 lbs/inch) afterthermal exposures during processing or use.

It may be beneficial to the electrical performance of any of thedisclosed shielded electrical cables for the pinched regions of thecable to have approximately the same size and shape on both sides of agiven conductor set. Any dimensional changes or imbalances may produceimbalances in capacitance and inductance along the length of the pinchedregion. This in turn may cause impedance differences along the length ofthe pinched region and impedance imbalances between adjacent conductorsets. At least for these reasons, control of the spacing between theshielding films may be desired. In some cases, the pinched portions ofthe shielding films in the pinched regions of the cable (on each side ofa conductor set) may be separated from each other by no more than about0.05 mm.

In FIG. 12, the far end crosstalk (FEXT) isolation is shown between twoadjacent conductor sets of a conventional electrical cable wherein theconductor sets are completely isolated, i.e., have no common ground(Sample 1), and between two adjacent conductor sets of the shieldedelectrical cable 1102 illustrated in FIG. 11 a wherein the shieldingfilms 1108 are spaced apart by about 0.025 mm (Sample 2), both having acable length of about 3 meters. The test method for creating this datais well known in the art. The data was generated using an Agilent 8720ES50 MHz-20 GHz S-Parameter Network Analyzer. It can be seen by comparingthe far end crosstalk plots that the conventional electrical cable andthe shielded electrical cable 1102 provide a similar far end crosstalkperformance. Specifically, it is generally accepted that a far endcrosstalk of less than about −35 dB is suitable for most applications.It can be easily seen from FIG. 12 that for the configuration tested,both the conventional electrical cable and shielded electrical cable1102 provide satisfactory electrical isolation performance. Thesatisfactory electrical isolation performance in combination with theincreased strength of the pinched portion due to the ability to spaceapart the shielding films is an advantage of at least some of thedisclosed shielded electrical cables over conventional electricalcables.

In exemplary embodiments described above, the shielded electrical cableincludes two shielding films disposed on opposite sides of the cablesuch that, in transverse cross section, cover portions of the shieldingfilms in combination substantially surround a given conductor set, andsurround each of the spaced apart conductor sets individually. In someembodiments, however, the shielded electrical cable may contain only oneshielding film, which is disposed on only one side of the cable.Advantages of including only a single shielding film in the shieldedcable, compared to shielded cables having two shielding films, include adecrease in material cost and an increase in mechanical flexibility,manufacturability, and ease of stripping and termination. A singleshielding film may provide an acceptable level of electromagneticinterference (EMI) isolation for a given application, and may reduce theproximity effect thereby decreasing signal attenuation. FIG. 13illustrates one example of such a shielded electrical cable thatincludes only one shielding film.

In FIG. 13 a shielded electrical cable 1302 having only one shieldingfilm 1308 is illustrated. Insulated conductors 1306 are arranged intotwo conductor sets 1304, each having only one pair of insulatedconductors, although conductor sets having other numbers of insulatedconductors as discussed herein are also contemplated. Shieldedelectrical cable 1302 is shown to include ground conductors 1312 invarious exemplary locations, but any or all of them may be omitted ifdesired, or additional ground conductors can be included. The groundconductors 1312 extend in substantially the same direction as insulatedconductors 1306 of conductor sets 1304 and are positioned betweenshielding film 1308 and a carrier film 1346 which does not function as ashielding film. One ground conductor 1312 is included in a pinchedportion 1309 of shielding film 1308, and three ground conductors 1312are included in one of the conductor sets 1304. One of these threeground conductors 1312 is positioned between insulated conductors 1306and shielding film 1308, and two of the three ground conductors 1312 arearranged to be generally co-planar with the insulated conductors 1306 ofthe conductor set.

In addition to signal wires, drain wires, and ground wires, any of thedisclosed cables can also include one or more individual wires, whichare typically insulated, for any purpose defined by a user. Theseadditional wires, which may for example be adequate for powertransmission or low speed communications (e.g. less than 1 or 0.5 Gbps,or less than 1 or 0.5 GHz, or in some cases less than 1 MHz) but not forhigh speed communications (e.g. greater than 1 Gpbs or 1 GHz), can bereferred to collectively as a sideband. Sideband wires may be used totransmit power signals, reference signals or any other signal ofinterest. The wires in a sideband are typically not in direct orindirect electrical contact with each other, but in at least some casesthey may not be shielded from each other. A sideband can include anynumber of wires such as 2 or more, or 3 or more, or 5 or more.

Section 2: Bending Characteristics of Shielded Electrical Cable

In the above described cable configurations, the shield is not a wrappedstructure but is arranged in two layers around the insulated wires. Thisshield structure may eliminate the resonance that afflicts helicallywrapped constructions, and may also exhibit bend behavior that is lessstiff than a wrapped construction and has superior retention ofelectrical performance after a sharp bend. These properties are enabledby, among other things, the use of a single ply thin shielding filmrather than an overlapped and an additional overwrapped film. Oneadvantage of this construction is that the cable can be bent sharply tomore effectively route the cable within a constrained space such aswithin a server, router, or other enclosed computer system.

In reference now to FIG. 14, a perspective view shows an application ofa shielded, high-speed, electrical ribbon cable 1402 according toexample embodiments. The cable 1402 may include any combination of thefeatures shown in FIGS. 1, 2 a-f, and 4 a-c, 8 a-b, 9, 10, 11 a-b, and13, but at least includes features shown in FIG. 2 b. The ribbon cable1402 is used to carry signals within a chassis 1404 or other object. Inmany situations, it is desirable to route the cable 1402 along sides ofthe chassis 1404. For example, such routing may allow cooling air tomore freely flow within the chassis 1404, ease access for maintenance,allow tighter spacing of components, improve appearance, etc.Accordingly, the cable 1402 may need to make sharp bends, such as cornerbends 1406 and 1408, e.g., to conform to structural features of thechassis 1404 and/or components contained therein. These bends 1406, 1408are shown as right angle (90 degree) bends, although the cable may bebent at sharper or broader angles in some applications.

In another application, an approximately 180 degree fold 1410 may beused to allow the cable 1402 to make a turn in a substantially planarspace. In such a case, the cable 1402 is folded across a fold line thatis at a particular angle relative to a longitudinal edge of the cable.In the illustrated fold 1410, the fold line is approximately 45 degreesrelative to such an edge, causing the cable 1402 to turn 90 degrees.Other fold angles may be used to form other turning angles as needed.Generally, the cable 1402 can configured to a given turn angle inresponse to proximate regions 1412, 1414 before and after the fold 1410being attached flat to a planar surface, e.g., a side of the chassis1404, or formed equivalently relative to a plane without being attachedto a surface.

In order for cable 1402 to be shaped as shown, the inner radii of bends1406, 1408 and folds 1410 may need to be relatively small. In FIGS. 15and 16, a side view shows cable 1402 bent/folded according to exampleembodiments. In FIG. 15, a 90 degree bend is shown, and in FIG. 16, a180-degree bend is shown. In both cases, an inner bend radius 1502 maybe a limiting factor when determining how flexible the cable is and howsuch bending may affect performance. The bend radius 1502 may bemeasured relative to a centerline 1504, which is parallel to and offsetfrom a fold line 1506 on the cable 1402. Both lines 1504 and 1506project orthogonally out of the page in this example, although mayproject at other angles for fold line angles different than 90 degrees.

For cables of constructions described here with conductors of wirediameter 24 American wire gauge (AWG) or less, the inner radius 1502 mayrange from 5 mm to 1 mm (or lower in some cases) without significantimpact to electrical performance (e.g., characteristic impedance, skew,attenuation loss, insertion loss, etc.). It is noted, that unlessotherwise stated, diameters of insulated conductors that are expressedin terms of AWG are intended to refer to a wire portion of the insulatedconductor, and not a diameter of the covering insulation.

Table 1 below illustrates expected maximum variations of some of thesecharacteristics for production cables having wire diameters of 24 AWG orless. These characteristics are measured for differential pairs ofconductors. While the cables may be capable of performance better thanillustrated in Table 1, these values may represent at least aconservative baseline usable for a system designer for estimatingperformance in production and/or deployment environments, and may stillrepresent a significant improvement over wrapped twinax cables commonlyused in similar environments.

TABLE 1 Variance of electrical characteristics for ribbon cable, 24 AWGor smaller, bend angle 180 degrees or less Inner bend Local differentialInsertion loss radius impedance variance variance 5 mm 1 ohm  0.1 dB 4mm 2 ohms 0.2 dB 3 mm 3 ohms 0.3 dB 2 mm 4 ohms 0.4 dB 1 mm 5 ohms 0.5dB

Generally, ribbon cables according to the embodiments discussed hereinmay be more flexible than conventional (e.g., wrapped) twinax cablesdesigned for high speed data transfer. This flexibility may be measuredin a number of ways, including defining a minimum bend radius 1502 for agiven conductor/wire diameter, definition of an amount of force neededto deflect the cable, and/or impact on electrical characteristics for agiven set of bending parameters. These and other characteristics will bediscussed in greater detail below.

In reference now to FIG. 17, a block diagram illustrates a test setup1700 for measuring force versus deflection of a cable 1402 according toan example embodiment. In this setup, the cable 1402 is initially laidflat across roller-type supports 1702 as indicated by dashed lines. Thesupports 1702 prevent downward motion, but otherwise allow free movementof the cable in a side-to-side direction. This may be analogous to theconstraint of a simply supported beam, e.g., a beam that has hingedconnection at one end and roller connection in other end, although inthe case of the cable there need be no side-to-side restraint such as ahinge might provide.

The supports 1702 in this test setup include 2.0 inch diameter cylindersseparated by a constant distance 1704 of 5.0 inches between the topsides of the cylinders (e.g., 12 o'clock position when viewed from theside as seen in FIG. 17). A force 1706 is applied to the cable 1402 viaa force actuator 1710 at a point equidistant between supports 1704, anddeflection 1708 is measured. The force actuator 1710 is a 0.375 inchdiameter cylinder, driven at a 5.0 inches per minute crosshead speed.

Results of a first test using setup 1700 for cables according toembodiments are shown in graph 1800 of FIG. 18. Curve 1802 representsforce-deflection results for a ribbon cable (e.g., similar toconfiguration 102 c in FIG. 2 c) with two solid 30 AWG conductors, solidpolyolefin insulation, and two 32 AWG drain wires. The maximum force isapproximately 0.025 lbf, and occurs at approximately 1.2 inches ofdeflection. By way of a rough comparison, curve 1804 was measured for awrapped twinax cable having two 30 AWG wires, and two 30 AWG drainwires. This curve has maximum force of around 0.048 lbs at a deflectionof 1.2 inches. All things being equal, it would be expected that thetwinax cable would be slightly stiffer due to the thicker (30 AWG vs. 32AWG) drain wires used, however this would not fully explain thesignificant difference between curves 1802 and 1804. Generally, it isexpected that the application of the force of 0.03 lbf on the cablerepresented by curve 1802 midpoint between the supporting points causesthe deflection in the direction of the force of at least 1 inch. Itshould be apparent that the cable represented by curve 1804 woulddeflect about half that much in response to the same 0.03 lbf force.

In FIG. 19, a graph 1900 shows results of a subsequent test of cablesaccording to example embodiments using the force deflection setup ofFIG. 17. For each of four wire gauges (24, 26, 30, and 32 AWG), fourcables were tested, each having two solid wire conductors of therespective gauges. The cables included polypropylene insulation on theconductors, shielding films on both sides of the cables, and no drainwires. The force was measured for every 0.2 inches of deflection. Table2 below summarizes the results at the maximum force points 1902, 1904,1906, 1908, which correspond to the results for the sets of cables withrespective wire gauge sizes of 24, 26, 30, and 32 AWG. The fifth andsixth columns of Table 2 correspond to the respective highest and lowestmaximum forces of the four cables tested within each gauge group.

TABLE 2 Force-deflection results for shielded ribbon cables with oneconductor pair. Conductor Deflection Average Standard Highest Lowestwire at maximum deviation max max gauge maximum force, F_(max) of forceforce (AWG) force (in.) (lbf) F_(max) (lbf) (lbf) (lbf) 24 1.2 0.2070.005 0.214 0.202 26 1.2 0.111 0.003 0.114 0.108 30 1.4 0.0261 0.0020.0284 0.0241 32 1.4 0.0140 0.0006 0.0149 0.0137

For the data in Table 2, it is possible to perform a linear regressionof the form y=m×+b on the logarithms of wire diameters versus thelogarithms of maximum deflection force. The natural logarithms (ln) ofthe forces in the third column of Table 2 are plotted versus naturallogarithms of the respective diameters in graph 2000 of FIG. 20. Thediameters of 24, 26, 30, and 32 AWG wires are 0.0201, 0.0159, 0.010, and0.008, respectively. A least squares linear regression of the curve ingraph 2000 results in the following fit: ln(Fmax)=2.96*ln(dia)+10.0. Bysolving for Fmax and rounding to two significant figures, the followingempirical result is obtained:

F _(max) =M*dia ³, where M=22,000 lbf/in ³  [1]

Equation [1] predicts that a similar cable made using two 28 AWGconductors (diameter=0.0126) would bend at a maximum force of22,000*0.01263=0.044 lbf. Such a result is reasonable in view of theresults for other gauges shown in FIG. 19. Further, Equation [1] may bemodified to express the individual maximum force (F_(max-single)) foreach single insulated conductor as follows:

F _(max-single) =M*dia ³, where M=11,000 lbf/in ³  [2]

The individual forces calculated from [2] for each insulated conductor(and drain wires or other non-insulated conductors) may be combined toobtain a collective maximum bending force for a give cable. For example,a combination of two 30 AWG and two 32 AWG wires would be expected tohave a maximum bending resistance force of 0.0261+0.014=0.0301 lbf. Thisis higher than the 0.025 lbf value seen in curve 1802 of FIG. 18 for thetested cable that had a combination of 30 AWG insulated wires and 32 AWGdrain wires. However, such a difference may be expected. The drain wiresin the tested cable are not insulated, thereby making the tested cablemore flexible than the theoretical case. Generally, the results ofEquations [1] and [2] are expected to return a high-end limit of bendingforces, which would still be more flexible than a conventional wrappedcable. By way of comparison, using Equation [2] for four 30 AWG wires,the maximum force would be 4*11,000*0.01=0.044 lbf, which is below whatis seen with the conventional wrapped cable test curve 1804 in FIG. 18.If the drain wires in the wrapped cable were insulated (which was notthe case) the curve 1804 would be expected exhibit an even highermaximum force.

A number of other factors could alter the results predicted by Equations[1] and [2], including the type of wire insulation (polyethylene andfoamed insulation would likely be less stiff, and fluoropolymerinsulation more stiff), the type of wire (stranded wires would be lessstiff), etc. Nonetheless, Equations [1] and [2] may provide a reasonableestimate of maximum bending forces for a given cable assembly, andpresent ribbon cable constructions exhibiting such properties should bemeasurably more flexible than equivalent wrapped constructions.

Also of interest in these cables is the minimum size of the radius 1506over which the cable 1402 may be bent/folded (see FIGS. 15 and 16)without significantly affecting electrical characteristics of the cable(e.g., impedance, crosstalk). These characteristics may be measuredlocally and/or over the entire cable. In reference now to FIG. 21, agraph 2100 illustrates bending performance of a cable according to anexample embodiment. Graph 2100 represents characteristic impedancemeasurements of a representative cable measured using a time domainreflectometer (TDR) with a rise time of 35 ps. Area 2102 represents anenvelope of differential impedance readings for a 100-ohm, solidconductor, differential pair, 30 AWG ribbon cable with a constructionsimilar to that of cable construction 102 c shown in FIG. 2 c. Theimpedance of the cable was measured in an initial, unbent state, andagain when the cable was bent once at 180-degree angle over a 1.0 mmbend radius. The bent-cable impedance measurement was made again afterthe cable was bent ten times over the same angle and radius. The timeregion 2104 indicated by the vertical dashed lines corresponds to alocation generally proximate to this bending.

The envelope 2102 represents an outline of the extremum of the measuredimpedance curves under all of the above described tests. This envelope2102 includes an impedance variance/discontinuity 2106 due to thebending. The variance 2106 is estimated to be approximately 0.5 ohms(peak impedance 95.9 ohms versus nominal 96.4 ohms in an unbentconfiguration at this location 2104). This variance 2106 was seen afterthe first bend, but not after the tenth, where no significant deviationfrom the envelope 2102 was seen. By way of comparison, a similar test,represented by envelope 2108, was performed on a conventional,helically-wrapped, 30 AWG, twinax cable. This measurement 2108 shows alocal impedance variance 2110 of approximately 1.6 ohms. The variance2110 not only is of greater magnitude than variance 2106, but is widerin the time scale, thereby affecting a larger region of the cable. Thisdeviation 2110 was also seen both in the first and tenth bendmeasurement of the conventional cable.

A similar set of impedance measurements was made for solid 26 AWG and 24AWG 100 ohm cables of similar construction to that of cable construction102 c shown in FIG. 2 c, except without drain wires 112 c. The 26 and 24AWG cables were bent 180 degrees over a 1.0 mm bend radius. Theresulting average variance was 0.71 ohms for the 26 AWG cable and 2.4ohms for the 24 AWG cable. Further, the 24 AWG was bent 180 degrees overa 2.0 mm radius, and the average variance was 1.7 ohms. Therefore acable of this construction should exhibit a variance of characteristicimpedance of no more than 2 ohms (or 2% of 100 ohm nominal impedance)proximate a 2.0 mm bend for conductor wire diameters of 24 AWG or less.Further, a cable of this construction should exhibit a variance ofcharacteristic impedance of no more than 1 ohms (or 2% of 100 ohmnominal impedance) proximate a 1.0 mm bend for conductor wire diametersof 26 AWG or less.

Although the measurements shown in graph 2100 are differential impedancemeasurements for cables with nominal 100 ohm characteristic impedance,the deviation/discontinuity 2106 is expected to scale linearly for othercable impedances and measurement techniques. For example, a 50 ohmsingle-ended impedance measurement (e.g., measuring just one wire of adifferential pair) would be expected to vary no more than 2% (1 ohm)proximate the bending for conductor wire diameters of 24 AWG or less,and 1% (0.5 ohm) for conductor wire diameters of 26 AWG or less. Similarscaling may be seen with different nominal values, e.g., 75 ohmcharacteristic differential impedance versus 100 ohms.

One possible reason for the improvement in impedance characteristics2102 of the representative ribbon cable compared to characteristics 2108of the wrapped cable is because of how the outer layers are formed onthe wrapped cable. Having a wrapped construction (e.g., individuallayers being overlapped, leading to more layers of covering) tends toincrease the stiffness of the wrap. This can pinch or “choke” the cablein the local area of a bend more than a ribbon cable with a singlelayer. Thus, all things being equal, a ribbon cable can be bent moresharply than a conventional cable with less effect on impedance. Theeffect of these impedance discontinuities is cumulative in the samecable, and so the ribbon cable can contain a greater number bends andstill function acceptably relative to a conventional wrapped cable. Thisimproved bend performance may be present whether the conductor set isalone (discrete), or in a ribbon cable with other conductor sets.

Among the benefits of a ribbon cable type construction are reduced laborand cost associated with terminating the cable. One connector of choicefor high speed connections is a printed circuit board (PCB) style“paddle-card” that connects to stamped contacts on the one or both sidesof the board. To facilitate this type of termination, the ground planesof the ribbon cable may be made easily strippable from the core and thecore can be made readily strippable from the wires. Lasers, fixtures,and mechanical cutting can be employed to make the process repeatableand fast.

Connection of the PCB to the cable ground planes can be accomplished byany number of methods such as conductive adhesives, conductive tapes,soldering, welding, ultrasound, mechanical clamping, etc. Likewise,connection of the conductors to the PCB can be accomplished usingsolder, welding, ultrasound, and other processes and is most efficientlydone all at once (gang bonding). In many of these configurations, thePCB has wire connections on both sides, therefore one or two such ribboncables can be used (one for each side) and can be stacked on top of oneanother in the cable.

In addition to the time savings that may be seen using ribbon cable topaddle card termination, the magnitude and length of any impedancediscontinuities or skew may be reduced at the termination site. Oneapproach used in terminating the cables is to limit the length ofconductor at the termination that is not impedance-controlled. This mayaccomplished by presenting the wire to the connection in roughly thesame format as the connector, which may include a linear array of traceswith pads on a PCB. The pitch of the cable may be able to be matchedwith the pitch of the PCB, thereby eliminating unequal and long exposedwire lengths needed when the cables do not have a matching pitch. Also,since the pitch can be made to match the board pitch, a length ofuncontrolled wire extending from the cable to the connector can beminimized.

Another benefit the cables described herein may exhibit with regards totermination is that folded portions of such cables can be encapsulatedin connectors. This may readily facilitate the formation of inexpensiveangled connectors. Various examples of connectors according to exampleembodiments are shown in FIGS. 22-27. In FIG. 22, connector assembly2200 terminates two layers of cable of previously described shieldedribbon cable configuration 1402. Some or all conductors of cables 1402are electrically coupled to the paddle card at top and bottomtermination areas 2204, 2206. The cables 1402 include bends at region2208 that facilitate routing the cables 1402 at a right angle relativeto the paddle card. An overmold 2210 encompasses at least the bendregion 2208, and may encompass at least part of the paddle card 2202(e.g., near termination areas 2204, 2206).

In FIG. 23, a connector assembly 2300 may include components similar to2200, except that a single shielded ribbon cable 1402 is used. Theassembly 2300 may include a similar overmold 2210, which in this exampleencompasses bend region 2302 and termination area 2204. FIGS. 24 and 25include connector assemblies 2400 and 2500 similar to 2300 and 1400,respectively, except that respective overmolds 2402 encompass bendregions 2404, 2502 with approximate 45 degree bends.

The connectors 2200, 2300, 2400, 2500 are all illustrated as terminatingconnectors, e.g., located at the end of a cable assembly. In somesituations, a connector may be desired at a middle portion of the cableassembly, which may include any non-terminal part of one or more cables1402 that make up the assembly. Examples of middle portion connectors2600 and 2700 are shown in FIGS. 26 and 27. In FIG. 26, a portion ofrespective cables 1402 may be broken off from the ribbon, bent at bendarea 2602 and terminated at termination areas 2204, 2206. An overmold2604 encompasses at least the bend area 2602, and also include an exitregion 2606 (e.g., strain relief) where unbent portions of ribbon cables1402 continue on. Cable 2700 is similar to cable 2600, except that oneof the ribbon cables 1402 is bent at region 2702 and terminated entirelyat area 2204. The other of the cables 1402 is not bent or terminated,but exits region 2606.

Those of ordinary skill in the art will appreciate that the featuresshown in FIGS. 22-27 are provided for purposes of illustration and notof limitation. It will be appreciated that many variations may existthat combine various disclosed features in FIGS. 22-27. For example, thebends in regions 2208, 2302, 2404, and 2502 may take on any angle andbend radius described herein for cable 1402 and equivalents. In anotherexample, while the illustrated connectors 2200, 2300, 2400, 2500, 2600,and 2700 are all shown using paddle cards 2206, other terminationstructures (e.g., crimped pins/sockets, insulation displacementconnections, solder cups, etc.) may be used for similar purposes withoutdeparting from the inventive scope of these embodiments. In yet anotherexample, the connectors 2200, 2300, 2400, 2500, 2600, and 2700 may usealternate casings/covers instead of overmolds, such as multi-piece,mechanically-attached housings, shrink wrap structures, bonded/adhesiveattached coverings, etc.

The foregoing description of the example embodiments has been presentedfor the purposes of illustration and description. It is not intended tobe exhaustive or to limit the invention to the precise form disclosed.Many modifications and variations are possible in light of the aboveteaching. It is intended that the scope of the invention be limited notwith this detailed description, but rather determined by the claimsappended hereto.

The following items are exemplary embodiments of a shielded electricalcable according to aspects of the present invention.

Item 1 is a shielded electrical cable, comprising: a plurality ofconductor sets extending along a length of the cable and being spacedapart from each other along a width of the cable, each conductor setincluding one or more insulated conductors; first and second shieldingfilms disposed on opposite sides of the cable, the first and secondfilms including cover portions and pinched portions arranged such that,in transverse cross section, the cover portions of the first and secondfilms in combination substantially surround each conductor set, and thepinched portions of the first and second films in combination formpinched portions of the cable on each side of each conductor set; and afirst adhesive layer bonding the first shielding film to the secondshielding film in the pinched portions of the cable; wherein: theplurality of conductor sets comprises a first conductor set thatcomprises neighboring first and second insulated conductors and hascorresponding first cover portions of the first and second shieldingfilms and corresponding first pinched portions of the first and secondshielding films forming a first pinched cable portion on one side of thefirst conductor set; a selected one of the insulated conductors has awire diameter no greater than 24 American wire gauge (AWG); and whereina transverse bending of the cable at a cable location of no more than180 degrees over an inner radius of at most 2 mm causes a cableimpedance of the selected insulated conductor proximate the cablelocation to vary by no more than 2 percent from an initial cableimpedance measured at the cable location in an unbent configuration.

Item 2 is a cable according to item 1, wherein the wire diameter of theselected insulated conductor is no greater than 26 AWG, and wherein atransverse bending of a cable location of no more than 180 degrees overan inner radius of at most 1 mm causes the cable impedance of theselected insulated conductor proximate the cable location to vary by nomore than 1 percent from the initial cable impedance.

Item 3 is a cable according to item 1, wherein the selected insulatedconductor is part of a selected one of the conductor sets that includesat least two insulated conductors each having a wire diameter no greaterthan 24 AWG and a nominal differential impedance of 100 ohms, andwherein the transverse bending of the cable causes a differential cableimpedance of the selected conductor set proximate the cable location tovary by no more than 2 ohms from an initial differential cable impedancemeasured at the cable location in the unbent configuration.

Item 4 is a cable according to item 3, wherein the wire diameter of theat least two insulated conductors is no greater than 26 AWG, and whereinthe transverse bending of a cable location of no more than 180 degreesover a second inner radius of at most 1 mm causes the differential cableimpedance of the selected conductor set proximate the cable location tovary by no more than 1 ohm from the initial differential impedance.

Item 5 is a cable according to items 1 or 2, wherein the selectedinsulated conductor has a nominal cable impedance of 50 ohms, andwherein the cable impedance of the selected insulated conductorproximate the cable location varies by no more than 1 ohm from theinitial cable impedance.

Item 6 is a cable according to any of items 1-5, wherein the cablefurther comprises a bend of at least 45 degrees around a fold line thatextends across a width of the cable, wherein the bend has an innerradius of at most 5 mm.

Item 7 is a cable according to item 6, wherein the bend is at least 90degrees and conforms to geometry of a structure that encloses the cable.

Item 8 is a cable according to item 6 or 7, wherein the bend is at least180 degrees and the fold line is at a fold angle relative to alongitudinal edge of the cable such that the cable turns at a turn anglein response to flattening of proximate regions before and after the bendto a plane.

Item 9 is a cable according to item 8, wherein the fold angle is 45degrees, and the turn angle is 90 degrees.

Item 10 is a shielded electrical cable, comprising: a plurality ofconductor sets extending along a length of the cable and being spacedapart from each other along a width of the cable, each conductor setincluding one or more insulated conductors; first and second shieldingfilms disposed on opposite sides of the cable, the first and secondfilms including cover portions and pinched portions arranged such that,in transverse cross section, the cover portions of the first and secondfilms in combination substantially surround each conductor set, and thepinched portions of the first and second films in combination formpinched portions of the cable on each side of each conductor set; and afirst adhesive layer bonding the first shielding film to the secondshielding film in the pinched portions of the cable; wherein: theplurality of conductor sets comprises a first conductor set thatcomprises neighboring first and second insulated conductors and hascorresponding first cover portions of the first and second shieldingfilms and corresponding first pinched portions of the first and secondshielding films forming a first pinched cable portion on one side of thefirst conductor set; a selected one of the insulated conductors has awire diameter no greater than 24 American wire gauge (AWG); and whereina transverse bending of the cable at a cable location of no more than180 degrees over an inner radius of at most 5 mm causes an insertionloss of the selected insulated conductor proximate the cable location tovary by no more than 0.5 dB from an initial insertion loss measured atthe cable location in an unbent configuration.

Item 11 is a cable according to item 10, wherein the cable furthercomprises a bend of at least 45 degrees around a fold line that extendsacross a width of the cable, wherein the bend has an inner radius of atmost 5 mm.

Item 12 is a cable according to item 11, wherein the bend is at least 90degrees and conforms to geometry of a structure that encloses the cable.

Item 13 is a cable according to item 11, wherein the bend is at least180 degrees and the fold line is at a fold angle relative to alongitudinal edge of the cable such that the cable turns at a turn anglein response to flattening of proximate regions before and after the bendto a plane.

Item 14 is a cable according to item 13, wherein the fold angle is 45degrees, and the turn angle is 90 degrees.

Item 15 is a shielded electrical cable, comprising: a plurality ofconductor sets extending along a length of the cable and being spacedapart from each other along a width of the cable, each conductor setincluding one or more insulated conductors; first and second shieldingfilms disposed on opposite sides of the cable, the first and secondfilms including cover portions and pinched portions arranged such that,in transverse cross section, the cover portions of the first and secondfilms in combination substantially surround each conductor set, and thepinched portions of the first and second films in combination formpinched portions of the cable on each side of each conductor set; and afirst adhesive layer bonding the first shielding film to the secondshielding film in the pinched portions of the cable; wherein: theplurality of conductor sets comprises a first conductor set thatcomprises neighboring first and second insulated conductors and hascorresponding first cover portions of the first and second shieldingfilms and corresponding first pinched portions of the first and secondshielding films forming a first pinched cable portion on one side of thefirst conductor set; and an application of a force on the cable, thecable being simply supported between two supporting points that are 3.0inches apart and the force being applied midpoint between the supportingpoints, results in a deflection in the direction of the force of atleast one inch, and wherein the force, measured in pounds-force, doesnot exceed the sum of individual forces for each of the insulatedconductors, the individual forces being equal to 11000 times a wirediameter cubed of the respective insulated conductor, the wire diameterbeing expressed in inches.

Item 16 is a cable according to item 15, wherein the wire diameter is nogreater than 24 American wire gauge (AWG).

Item 17 is a cable according to item 15 or 16, wherein the maximum forceoccurs when the deflection is between 1 inch and 1.5 inches.

Item 18 is a cable according to any of items 15-17, wherein the cablefurther comprises a bend of at least 45 degrees around a fold line thatextends across a width of the cable, wherein the bend has an innerradius of at most 5 mm.

Item 19 is a cable according to item 18, wherein the bend is at least 90degrees and conforms to geometry of a structure that encloses the cable.

Item 20 is a cable according to item 18, wherein the bend is at least180 degrees and the fold line is at a fold angle relative to alongitudinal edge of the cable such that the cable turns at a turn anglein response to flattening of proximate regions before and after the bendto a plane.

Item 21 is a cable according to item 20, wherein the fold angle is 45degrees, and the turn angle is 90 degrees.

Item 22 is a cable assembly, comprising: a shielded electrical cablecomprising: a plurality of conductor sets extending along a length ofthe cable and being spaced apart from each other along a width of thecable, each conductor set including one or more insulated conductors;first and second shielding films disposed on opposite sides of thecable, the first and second films including cover portions and pinchedportions arranged such that, in transverse cross section, the coverportions of the first and second films in combination substantiallysurround each conductor set, and the pinched portions of the first andsecond films in combination form pinched portions of the cable on eachside of each conductor set; a first adhesive layer bonding the firstshielding film to the second shielding film in the pinched portions ofthe cable; and a bend in the cable of at least 45 degrees around a foldline that extends across a width of the cable, wherein the bend has aninner radius of at most 5 mm; wherein: the plurality of conductor setscomprises a first conductor set that comprises neighboring first andsecond insulated conductors and has corresponding first cover portionsof the first and second shielding films and corresponding first pinchedportions of the first and second shielding films forming a first pinchedcable portion on one side of the first conductor set; and an electricalconnector encompassing at least the bend in the cable, wherein at leastone of the insulated conductors is electrically coupled to at least onecontact of the electrical connector.

Item 23 is a cable assembly according to item 22, wherein the electricalconnector comprises an overmold formed onto the cable.

Item 24 is a cable assembly according to items 22-23, wherein theelectrical connector comprises a multi-piece housing.

Item 25 is a cable assembly according to any of items 22-24, wherein theconnector comprises a paddle card connector.

Item 26 is a cable assembly according to any of items 22-24, wherein thebend is at least 90 degrees around the fold line.

Item 27 is a cable assembly according to item 26, wherein the innerradius of the bend is at most 1 mm.

Item 28 is a cable assembly according to any of items 22-25, wherein theinner radius of the bend is at most 1 mm.

Item 29 is a cable assembly according to any of items 22-28, wherein theconnector is disposed on an end of the cable.

Item 30 is a cable assembly according to any of items 22-28, wherein theconnector is disposed on a middle portion of the cable.

Item 31 is a cable assembly according to any of items 22-30, wherein theinsulated conductors have a wire diameter of no more than 24 Americanwire gauge (AWG).

Item 32 is a cable assembly according to any of items 22-31, wherein thecable further comprises a second bend not encompassed by the electricalconnector, the second bend being of at least 45 degrees around a secondfold line that extends across a width of the cable, wherein the secondbend has an inner radius of at most 5 mm.

Item 33 is a cable assembly according to item 32, wherein the secondbend is at least 90 degrees and conforms to geometry of a structure thatencloses the cable assembly.

Item 34 is a cable assembly according to item 32, wherein the secondbend is at least 180 degrees and the second fold line is at a fold anglerelative to a longitudinal edge of the cable such that the cable turnsat a turn angle in response to flattening of proximate regions beforeand after the second bend to a plane.

Item 35 is a cable assembly according to item 34, wherein the secondfold angle is 45 degrees, and the turn angle is 90 degrees.

Item 36 is the cable assembly according to any of items 22-35, whereinthe at least one conductor set is adapted for maximum data transmissionrates of at least 1 Gb/s.

Although specific embodiments have been illustrated and described hereinfor purposes of description of the preferred embodiment, it will beappreciated by those of ordinary skill in the art that a wide variety ofalternate and/or equivalent implementations calculated to achieve thesame purposes may be substituted for the specific embodiments shown anddescribed without departing from the scope of the present invention.Those with skill in the mechanical, electro-mechanical, and electricalarts will readily appreciate that the present invention may beimplemented in a very wide variety of embodiments. This application isintended to cover any adaptations or variations of the preferredembodiments discussed herein. Therefore, it is manifestly intended thatthis invention be limited only by the claims and the equivalentsthereof.

What is claimed is:
 1. A shielded electrical cable, comprising: aplurality of differential pairs extending along a length of the cableand being arranged generally in a plane along a width of the cable, eachdifferential pair including two insulated conductors having wirediameters not greater than 24 American Wire Gauge (AWG), eachdifferential pair being substantially surrounded by a shield; first andsecond non-conductive polymeric layers disposed on opposite sides of thecable, the first and second layers including cover portions and pinchedportions arranged such that, in transverse cross section, the coverportions of the first and second layers in combination substantiallysurround the plurality of differential pairs, and the pinched portionsof the first and second layers in combination form pinched portions ofthe cable on each side of the plurality of differential pairs; and anadhesive layer bonding the first non-conductive polymeric layer to thesecond non-conductive polymeric layer in the pinched portions of thecable; wherein a transverse bending of the cable at a cable location of180 degrees over an inner radius of at most 2 mm causes a cableimpedance of the insulated conductors of the differential pairsproximate the cable location to vary by no more than 2 percent from aninitial cable impedance measured at the cable location in an unbentconfiguration.
 2. A cable according to claim 1, wherein the wirediameter of the insulated conductor of each differential pair is notgreater than 26 AWG, and wherein a transverse bending of the cable at acable location of no more than 180 degrees over an inner radius of atmost 1 mm causes the insulated conductors of the differential pairsproximate the cable location to vary by no more than 1 percent from theinitial cable impedance.
 3. A cable according to claim 1, wherein eachinsulated conductor of each differential pair has a wire diameter notgreater than 24 AWG and a nominal differential impedance of 100 ohms,and wherein a transverse bending of the cable causes a differentialcable impedance of the insulated conductors of the differential pairsproximate the cable location to vary by no more than 2 ohms from aninitial differential cable impedance measured at the cable location inthe unbent configuration.
 4. A cable according to claim 1, wherein thecable further comprises a bend of at least 45 degrees around a fold linethat extends across a width of the cable, wherein the bend has an innerradius of at most 5 mm.
 5. A shielded electrical cable, comprising: aplurality of differential pairs extending along a length of the cableand being arranged generally in a plane along a width of the cable, eachdifferential pair including two insulated conductors having wirediameters not greater than 24 American Wire Gauge (AWG), eachdifferential pair being substantially surrounded by a shield; first andsecond non-conductive polymeric layers disposed on opposite sides of thecable, the first and second layers including cover portions and pinchedportions arranged such that, in transverse cross section, the coverportions of the first and second layers in combination substantiallysurround the plurality of differential pairs, and the pinched portionsof the first and second layers in combination form pinched portions ofthe cable on each side of the plurality of differential pairs; and anadhesive layer bonding the first non-conductive polymeric layer to thesecond non-conductive polymeric layer in the pinched portions of thecable; wherein a transverse bending of the cable at a cable location of90 degrees over an inner radius of at most 5 mm causes an insertion lossof the insulated conductors of the differential pairs proximate thecable location to vary by no more than 0.5 dB from an initial insertionloss measured at the cable location in an unbent configuration.
 6. Acable according to claim 5, wherein the cable further comprises a bendof at least 45 degrees around a fold line that extends across a width ofthe cable, wherein the bend has an inner radius of at most 5 mm.
 7. Acable assembly, comprising: a shielded electrical cable comprising: aplurality of differential pairs extending along a length of the cableand being arranged generally in a plane along a width of the cable, eachdifferential pair including two insulated conductors having wirediameters not greater than 24 American Wire Gauge (AWG), eachdifferential pair being substantially surrounded by a shield; first andsecond non-conductive polymeric layers disposed on opposite sides of thecable, the first and second layers including cover portions and pinchedportions arranged such that, in transverse cross section, the coverportions of the first and second layers in combination substantiallysurround the plurality of differential pairs, and the pinched portionsof the first and second layers in combination form pinched portions ofthe cable on each side of the plurality of differential pairs; anadhesive layer bonding the first non-conductive polymeric layer to thesecond non-conductive polymeric layer in the pinched portions of thecable; and a bend in the cable of 45 or 90 degrees around a fold linethat extends across a width of the cable, wherein the bend has an innerradius of at most 5 mm; and an electrical connector encompassing atleast the bend in the cable, wherein at least one of the insulatedconductors is electrically coupled to at least one contact of theelectrical connector.
 8. A cable assembly according to claim 7, whereinthe electrical connector comprises an overmold formed onto the cable. 9.A cable assembly according to claim 7, wherein the cable furthercomprises a second bend not encompassed by the electrical connector, thesecond bend being of at least 45 degrees around a second fold line thatextends across a width of the cable, wherein the second bend has aninner radius of at most 5 mm.